Therefore my heart is glad. In this verse the Psalmist commends the inestimable fruit of faith, of which Scripture every where makes mention, in that, by placing us under the protection of God, it makes us not only to live in the enjoyment of mental tranquillity, but, what is more, to live joyful and cheerful. The principal, the essential part of a happy life, as we know, is to possess tranquillity of conscience and of mind; as, on the contrary, there is no greater infelicity than to be tossed amidst a multiplicity of cares and fears. But the ungodly, however much intoxicated with the spirit of thoughtlessness or stupidity, never experience true joy or serene mental peace; they rather feel terrible agitations within, which often come upon them and trouble them, so much as to constrain them to awake from their lethargy. In short, calmly to rejoice is the lot of no man but of him who has learned to place his confidence in God alone, and to commit his life and safety to his protection. When, therefore, encompassed with innumerable troubles on all sides, let us be persuaded, that the only remedy is to direct our eyes towards God; and if we do this, faith will not only tranquillise our minds, but also replenish them with fullness of joy. David, however, not only affirms that he is glad inwardly; he also makes his tongue, yea, even his flesh, sharers of this joy. And not without cause, for true believers not only have this spiritual joy in the secret affection of their heart, but also manifest it by the tongue, inasmuch as they glory in God as He who protects them and secures their salvation. The word kvvd, kabod, properly signifies glory and excellence. I have, however, no doubt of its being here taken for the tongue, [1] as it is in Genesis 49:6; for otherwise the division which is obviously made in this verse of the person into three parts is not so distinct and evident. Farther, although the body is not free from inconveniences and troubles, yet as God defends and maintains not only our souls, but also our bodies, David does not speak groundlessly when he represents the blessing of dwelling in safety as extending to his flesh in common with his soul.

Footnotes

1 - The reading of the Septuagint is, "glossa mou" "my tongue." This is unquestionably the meaning. David uses the word glory for the organ by which God is glorified or praised. The Apostle Peter, in quoting this passage, (Acts 2:26,) reads, "my tongue." See also Psalm 36:12

Therefore my heart is glad - In view of this fact, that my confidence is in God alone, and my belief that he is my Protector and Friend. See the notes at Acts 2:26.
And my glory rejoiceth - The Septuagint translate this, "my tongue," and this translation is followed by Peter in his quotation of the passage in Acts 2:26. See the notes at that passage. The meaning here is, that whatever there was in him that was honorable, dignified, or glorious - all the faculties of his soul, as well as his heart - had occasion to rejoice in God. His whole nature - his undying soul - his exalted powers as he was made by God - all - all, found cause of exultation in the favor and friendship of God. The heart - the uuderstanding - the imagination - the whole immortal soul, found occasion for joy in God.
My flesh also - My body. Or, it may mean, his whole person, he himself, though the direct allusion is to the body considered as lying in the grave, Psalm 16:10. The language is such as one would use of himself when he reflected on his own death, and it is equivalent to saying, "I myself, when I am dead, shall rest in hope; my soul will not be left to abide in the gloomy place of the dead; nor will my body remain permanently in the grave under the power of corruption. In reference to my soul and my body - my whole nature - I shall descend to the grave in the hope of a future life."
Shall rest - Margin, "dwell confidently." The Hebrew is literally "shall dwell in confidence" or hope. The word here rendered "shall rest" means properly to let oneself down; to lie down, Numbers 9:17; Exodus 24:16; then, to lay oneself down, to lie down, as, for example, a lion lying down, Deuteronomy 33:20; or a people in tents, Numbers 24:2; and hence, to rest, to take rest, Judges 5:17; and then to abide, to dwell. Gesenius, Lexicon. Perhaps the sense here is that of "lying down," considered as lying in the grave, and the expression is equivalent to saying, "When I die I shall lie down in the grave in hope or confidence, not in despair. I shall expect to rise and live again."
In hope - The word used here means "trust, confidence, security." It is the opposite of despair. As used here, it would refer to a state of mind in which there was an expectation of living again, as distinguished from that state of mind in which it was felt that the grave was the end of man. What is particularly to be remarked here is, that this trust or confidence extended to the "flesh" as well as to the "soul;" and the language is such as would be naturally used by one who believed in the resurrection of the body. Language of this kind occurs elsewhere in the Old Testament, showing that the doctrine of the resurrection of the body was one to which the sacred writers were not strangers, and that although the doctrine was not as explicitly and formally stated in the Old Testament as in the New, yet that it was a doctrine which had been at some time communicated to man. See Isaiah 26:19, note; Daniel 12:2, note. As applicable to David, the language used here is expressive of his belief that "he" would rise again, or would not perish in the grave when his body died; as applicable to the Messiah, as applied by Peter Acts 2:26, it means that when "he" should die it would be with the hope and expectation of being raised again without seeing corruption. The language is such as to be applicable to both cases; and, in regard to the interpretation of the "language," it makes no difference whether it was supposed that the resurrection would occur before the body should moulder back to dust, or whether it would occur at a much more remote period, and long after it had gone to decay. In either case it would be true that it was laid in the grave "in hope."

Therefore my heart is glad - Unutterably happy in God; always full of the Divine presence; because whatsoever I do pleaseth him. The man Christ Jesus must be constantly in communion with God, because he was without spot and blemish.
My glory rejoiceth - My tongue, so called by the Hebrews, (see Psalm 57:8; Psalm 30:12), because it was bestowed on us to glorify God, and because it is our glory, being the instrument of expressing our thoughts by words. See Dodd. But soul bids as fair to be the meaning. See the notes on Acts 2:25, etc.
My flesh also shall rest in hope - There is no sense in which these and the following words can be spoken of David. Jesus, even on the cross, and breathing out his soul with his life, saw that his rest in the grave would be very short: just a sufficiency of time to prove the reality of his death, but not long enough to produce corruption; and this is well argued by St. Peter, Acts 2:31.

Therefore (h) my heart is glad, and my glory rejoiceth: my flesh also shall rest in hope.
(h) That is, I rejoice both in body and in soul.

Therefore my heart is glad,.... Because he had the Lord always in view; he was at his right hand, for his support and assistance, as well as because of what is expressed in the next verses: this is the same with rejoicing in spirit, Luke 10:21; it denotes an inward joy, and fulness of it, because of the Lord's presence with him; see Acts 2:28;
and my glory rejoiceth; meaning either his soul, which is the most glorious and noble part of man, as Aben Ezra, Kimchi, and Ben Melech interpret it; or rather his tongue, as in Acts 2:26; the faculty of speaking in man being what gives him a superior glory and excellency to other creatures, and is that whereby he glorifies God; and so the word is often used in this book; see Psalm 30:12; and here the phrase designs Christ's glorifying God, and singing his praise with joyful lips, among his disciples, a little before his sufferings and death;
my flesh also shall rest in hope; in the grave, which, as it is a resting place to the members of Christ, from all their sorrow, toil, and labour here; so it was to Christ their head, who rested in it on the Jewish sabbath, that day of rest, and that berth "in safety" (t), as the word used may signify, and in of his resurrection from the dead, as follows.
(t) "in tuto", Tigurine version; "secure", Junius & Tremellius, Piscator, Cocceius; "in confidence", Ainsworth.

glory--as heart (Psalm 7:5), for self. In Acts 2:26, after the Septuagint, "my tongue" as "the glory of the frame"--the instrument for praising God.
flesh--If taken as opposed to soul (Psalm 16:10), it may mean the body; otherwise, the whole person (compare Psalm 63:1; Psalm 84:2).
rest in hope--(compare Margin).

Thus then, as this concluding strophe, as it were like seven rays of light, affirms, he has the most blessed prospect before him, without any need to fear death. Because Jahve is thus near at hand to help him, his heart becomes joyful (שׂמח) and his glory, i.e., his soul (vid., on Psalm 7:6) rejoices, the joy breaking forth in rejoicing, as the fut. consec. affirms. There is no passage of Scripture that so closely resembles this as 1-Thessalonians 5:23. לב is πνεῦμα (νοῦς), כבוד, ψυχή (vid., Psychol. S. 98; tr. p. 119), בּשׂר (according to its primary meaning, attrectabile, that which is frail), σῶμα. The ἀμέμπτως τηρηθῆναι which the apostle in the above passage desires for his readers in respect of all three parts of their being, David here expresses as a confident expectation; for אף implies that he also hopes for his body that which he hopes for his spirit-life centred in the heart, and for his soul raised to dignity both by the work of creation and of grace. He looks death calmly and triumphantly in the face, even his flesh shall dwell or lie securely, viz., without being seized with trembling at its approaching corruption. David's hope rests on this conclusion: it is impossible for the man, who, in appropriating faith and actual experience, calls God his own, to fall into the hands of death. For Psalm 16:10 shows, that what is here thought of in connection with שׁכן לבטח, dwelling in safety under the divine protection (Deuteronomy 33:12, Deuteronomy 33:28, cf. Proverbs 3:24), is preservation from death. שׁחת is rendered by the lxx διαφθορά, as though it came from שׁחת διαφθείρειν, as perhaps it may do in Job 17:14. But in Psalm 7:16 the lxx has βόθρος, which is the more correct: prop. a sinking in, from שׁוּח to sink, to be sunk, like נחת from נוּח, רחת from רוּח. To leave to the unseen world (עזב prop. to loosen, let go) is equivalent to abandoning one to it, so that he becomes its prey. Psalm 16:10 - where to see the grave (Psalm 49:10), equivalent to, to succumb to the state of the grave, i.e., death (Psalm 89:49; Luke 2:26; John 8:51) is the opposite of "seeing life," i.e., experiencing and enjoying it (Ecclesiastes 9:9, John 3:36), the sense of sight being used as the noblest of the senses to denote the sensus communis, i.e., the common sense lying at the basis of all feeling and perception, and figuratively of all active and passive experience (Psychol. S. 234; tr. p. 276) - shows, that what is said here is not intended of an abandonment by which, having once come under the power of death, there is no coming forth again (Bttcher). It is therefore the hope of not dying, that is expressed by David in Psalm 16:10. for by חסידך David means himself. According to Norzi, the Spanish MSS have חסידיך with the Masoretic note יתיר יוד, and the lxx, Targ., and Syriac translate, and the Talmud and Midrash interpret it, in accordance with this Ker. There is no ground for the reading חסידיך, and it is also opposed by the personal form of expression surrounding it.
(Note: Most MSS and the best, which have no distinction of Ker and Chethb here, read חסידך, as also the Biblia Ven. 1521, the Spanish Polyglott and other older printed copies. Those MSS which give חסידיך (without any Ker), on the other hand, scarcely come under consideration.)
The positive expression of hope in Psalm 16:11 comes as a companion to the negative just expressed: Thou wilt grant me to experience (הודיע, is used, as usual, of the presentation of a knowledge, which concerns the whole man and not his understanding merely) ארח חיּים, the path of life, i.e., the path to life (cf. Proverbs 5:6; Proverbs 2:19 with ib. Psalm 10:17; Matthew 7:14); but not so that it is conceived of as at the final goal, but as leading slowly and gradually onwards to life; חיּים in the most manifold sense, as, e.g., in Psalm 36:10; Deuteronomy 30:15 : life from God, with God, and in God, the living God; the opposite of death, as the manifestation of God's wrath and banishment from Him. That his body shall not die is only the external and visible phase of that which David hopes for himself; on its inward, unseen side it is a living, inwrought of God in the whole man, which in its continuance is a walking in the divine life. The second part of Psalm 16:11, which consists of two members, describes this life with which he solaces himself. According to the accentuation, - which marks חיים with Olewejored not with Rebia magnum or Pazer, - שׂבע שׂמחות is not a second object dependent upon תּודיעני, but the subject of a substantival clause: a satisfying fulness of joy is את־פּניך, with Thy countenance, i.e., connected with and naturally produced by beholding Thy face (את preposition of fellowship, as in Psalm 21:7; 140:14); for joy is light, and God's countenance, or doxa, is the light of lights. And every kind of pleasurable things, נעמות, He holds in His right hand, extending them to His saints - a gift which lasts for ever; נצח equivalent to לנצח. נצח, from the primary notion of conspicuous brightness, is duration extending beyond all else - an expression for לעולם, which David has probably coined, for it appears for the first time in the Davidic Psalm. Pleasures are in Thy right hand continually - God's right hand is never empty, His fulness is inexhaustible.
The apostolic application of this Psalm (Acts 2:29-32; Acts 13:35-37) is based on the considerations that David's hope of not coming under the power of death was not realised in David himself, as is at once clear, to the unlimited extent in which it is expressed in the Psalm; but that it is fulfilled in Jesus, who has not been left to Hades and whose flesh did not see corruption; and that consequently the words of the Psalm are a prophecy of David concerning Jesus, the Christ, who was promised as the heir to his throne, and whom, by reason of the promise, he had prophetically before his mind. If we look into the Psalm, we see that David, in his mode of expression, bases that hope simply upon his relation to Jahve, the ever-living One. That it has been granted to him in particular, to express this hope which is based upon the mystic relation of the חסיד to Jahve in such language, - a hope which the issue of Jesus' life has sealed by an historical fulfilment, - is to be explained from the relation, according to the promise, in which David stands to his seed, the Christ and Holy One of God, who appeared in the person of Jesus. David, the anointed of God, looking upon himself as in Jahve, the God who has given the promise, becomes the prophet of Christ; but this is only indirectly, for he speaks of himself, and what he says has also been fulfilled in his own person. But this fulfilment is not limited to the condition, that he did not succumb to any peril that threatened his life so long as the kingship would have perished with him, and that, when he died, the kingship nevertheless remained (Hofmann); nor, that he was secured against all danger of death until he had accomplished his life's mission, until he had fulfilled the vocation assigned to him in the history of the plan of redemption (Kurtz) - the hope which he cherishes for himself personally has found a fulfilment which far exceeds this. After his hope has found in Christ its full realisation in accordance with the history of the plan of redemption, it receives through Christ its personal realisation for himself also. For what he says, extends on the one hand far beyond himself, and therefore refers prophetically to Christ: in decachordo Psalterio - as Jerome boldly expresses it - ab inferis suscitat resurgentem. But on the other hand that which is predicted comes back upon himself, to raise him also from death and Hades to the beholding of God. Verus justitiae sol - says Sontag in his Tituli Psalmorum, 1687 - e sepulcro resurrexit, στήλη seu lapis sepulcralis a monumento devolutus, arcus triumphalis erectus, victoria ab hominibus reportata. En vobis Michtam! En Evangelium! -

My glory - My tongue, which is a man's glory and privilege, above all other living creatures. Rejoiceth - Declares my inward joy. For this word signifies not so much eternal joy, as the outward demonstrations of it. My flesh - My body shall quietly rest in the grave. Shall rest - in confident assurance of its incorruption there, and of its resurrection to an immortal life: the flesh or body is in itself, but a dead lump of clay; yet hope is here ascribed to it figuratively, as it is to the brute creatures, Romans 8:19.