He concludes, by stating, that as he is protected by the power of God, he enjoys as much security and quiet as if he had been defended by all the garrisons on earth. Now, we know, that to be free from all fear, and from the torment and vexation of care, is a blessing to be desired above all other things. This verse, therefore, is a confirmation of the former sentence, intimating that David justly prefers the joy produced by the light of God's fatherly love before all other objects for inward peace of mind certainly surpasses all the blessings of which we can form any conception. Many commentators explain this place as expressing David's hope, that his enemies will be reconciled to him, so that he may sleep with them in peace, God having granted him the peculiar privilege of being able to rest without being disturbed or disquieted by any man. But in my judgment the proper meaning is this, that he will live as quietly and securely alone, as in the midst of a great host of men, because God defends him for in the words, I will sleep together, I consider the particle as to be understood, as if the reading were as together, that is to say, as with a multitude. Some refer lvdd, lebadad, alone, to God, translating the words thus, Thou alone, O Lord, hast set me in safety; but this I do not at all approve, because, by taking away the contrast between these two words, together and alone, much of the beauty of the sentence is lost. In short, David boasts that the protection of God alone was sufficient, and that under it he sleeps as securely, although destitute of all human guardianship, as if he had had many to keep watch and ward continually over him, or as if he had been defended on all sides by a great company. Let us therefore, learn from his example, to yield this honor to God -- to believe, that although there may appear no help for us from men, yet under his hand alone we are kept in peace and safety, as if we were surrounded by a great host.

I will both lay me down in peace, and sleep - The word "both" here means "at the same time;" that is, I will alike be in peace, and I will lie down and will sleep; I will have a mind at peace (or, in tranquility) when I lie down, and will sleep calmly. This is said in view of his confidence in God, and of his belief that God would preserve him. He had put his trust in him; he had sought his happiness in him, and now he felt assured that he had nothing to fear, and, at peace with God, he would lie down and compose himself to rest. This is the counterpart of what is said in Psalm 3:5. There he says in the morning, that, though surrounded by fear, he "had" been permitted to lie calmly down and sleep; here he says, that, though he is surrounded by fear, he has such confidence in God, that he "will" give himself to quiet slumber. His mind was free from anxiety as to the result of the present troubles; he had calm confidence in God; he committed all to him; and thus gave himself to rest. No one can fail to admire the beauty of this; and no one can fail to perceive that entire confidence in God, and an assurance that all things are under his control, are best adapted of all things to give peaceful days and nights.
For thou, Lord, only makest me dwell in safety - There are two ideas here:
(a) One a confidence that he would abide in safety;
(b) the other, that he owed this entirely to the Lord.
He had no power to defend himself, and yet he felt assured that he would be safe - for he put his trust entirely in the Lord. The whole language implies unwavering trust or confidence in God, and is thus instructive and useful for all. It teaches us:
(1) that in the midst of troubles we may put our trust in God; and
(2) that religion is adapted to make the mind calm in such circumstances, and to enable its possessor to lie down without anxiety in the slumbers of the night, and to pursue without anxiety the duties of the day.

I will both lay me down in peace, and sleep - Most men lie down, and most sleep, daily, for without rest and steep life could not be preserved; but alas! how few lie down in peace! peace with their own consciences, and peace with God! David had then two great blessings, rest by sleep, and peace in his soul. He had a happy soul; and when he lay down on his bed, his body soon enjoyed its repose, as the conscience was in peace. And he had a third blessing, a confidence that he should sleep in safety. And it was so. No fearful dreams disturbed his repose, for he had a mind tranquillized by the peace of God. As to his body, that enjoyed its due rest, for he had not overloaded nature either with dainties or superfluities. Reader, are not many of thy sleepless hours to be attributed to thy disordered soul - to a sense of guilt on thy conscience, or to a fear of death and hell?
Pray incessantly till thou get the light of God's countenance, till his Spirit bear witness with thine that thou art a child of God. Then thy repose will do thee good: and even in thy sleep thy happy soul will be getting forward to heaven.

I will both lay me down in peace, and sleep: for thou, LORD, (l) only makest me dwell in safety.
(l) This word in Hebrew may be referred to God, as it is here translated, or to David, signifying that he should dwell as joyfully alone, as if he had many about him, because the Lord is with him.

I will both lay me down in peace, and sleep,.... Signifying, that he had such a calmness and serenity of mind, amidst all his troubles, that he could not only lay himself down in great peace, and much composure of mind, but sleep also, and that as soon as laid down almost; some lay themselves down, but cannot sleep, through the anxiety of their minds; but the psalmist could do both: or the word rendered "both" may he translated "together" (u); and the sense be either that he would lie down and sleep together with his friends, committing himself and them to the care and protection of God; or that he should lie down and sleep together with his enemies; meaning that he was assured that there would quickly be a reconciliation and peace between them; see Proverbs 16:7;
for thou, Lord, only makest me dwell in safety; suggesting that his protection and safety were owing to the power and presence of God only; and that was the reason of the tranquillity of his mind, and why he slept so quietly in the night watches, though in such danger from his enemies; or "thou, Lord, makest me only" or "alone" (w), being solitary and destitute of friends, to dwell in safety; finder the shadow of thy wings, encompassed by thy favour, and surrounded by thy power; see Deuteronomy 33:28.
(u) "simul", Musculus, Junius & Tremellius, Piscator, Gejerus, Cocceius. (w) "me solum", Cocceius; "me seorsim", Gejerus.

both lay me down, &c.--or, will lie down at once, and sleep in sure confidence and quiet repose (Psalm 3:5).

(Hebrews.: 4:9) Thus then he lies down to sleep, cheerfully and peacefully. The hymn closes as it began with a three line verse. יחדּוּ (lit., in its unions = collectively, Olshausen, 135, c, like כּלּו altogether, בּעתּו at the right time) is by no means unemphatic; nor is it so in Psalm 19:10 where it means "all together, without exception." With synonymous verbs it denotes the combination of that which they imply, as Isaiah 42:14. It is similar in Psalm 141:10 where it expresses the coincidence of the fall of his enemies and the escape of the persecuted one. So here: he wishes to go to sleep and also at once he falls asleep (ואישׁן in a likewise cohortative sense = ואישׁנה). His God makes him to dwell in seclusion free of care. לברד is a first definition of condition, and לבטח a second. The former is not, after Deuteronomy 32:12, equivalent to לבדּך, an addition which would be without any implied antithesis and consequently meaningless. One must therefore, as is indeed required by the situation, understand לבדד according to Numbers 23:9; Micah 7:14; Deuteronomy 33:28; Jeremiah 49:31. He needs no guards for he is guarded round about by Jahve and kept in safety. The seclusion, בּדד, in which he is, is security, בּטח, because Jahve is near him. Under what a many phases and how sweetly the nature of faith is expressed in this and the foregoing Psalm: his righteousness, exaltation, joy, peace, contentment in God! And how delicately conceived is the rhythm! In the last line the evening hymn itself sinks to rest. The iambics with which it closes are like the last strains of a lullaby which die away softly and as though falling asleep themselves. Dante is right when he says in his Convito, that the sweetness of the music had harmony of the Hebrew Psalter is lost in the Greek and Latin translations.

In peace - In tranquility of mind, resting securely upon God's promises.