Then said I, Lo, I come (in the volume of the book it is written of me,) to do thy will, O God.

Then said I, Lo, I am come (In the roll of the book it is written of me) To do thy will, O God.

Then said I: Behold I come: in the head of the book it is written of me: that I should do thy will, O God.

Then said I, Lo, I come (in the volume of the book it is written concerning me,) to do thy will, O God.

Then I said, 'I have come - in the roll of the book it is written concerning Me - to do Thy will, O God.'"

Then I said, See, I have come to do your pleasure, O God (as it is said of me in the roll of the book).

Then I said, 'Behold, I draw near.' At the head of the book, it has been written of me that I should do your will, O God."

Tunc dixi, Ecce adsum; in capite libri scriptum est de me, ut faciam, O Deus, voluntatem tuam.

In the volume or chapter of the book, etc. Volume is properly the meaning of the Hebrew word; for we know that books were formerly rolled up in the form of a cylinder. There is also nothing unreasonable in understanding book as meaning the Law, which prescribes to all God's children the rule of a holy life; though it seems to me a more suitable view to consider him as saying, that he deemed himself to be in the catalogue of those who render themselves obedient to God. The Law, indeed, bids us all to obey God; but David means, that he was numbered among those who are called to obey God; and then he testifies that he obeyed his vocation, by adding, I come to do thy will; and this peculiarly belongs to Christ. For though all the saints aspire after the righteousness of God, yet it is Christ alone who was fully competent to do God's will. This passage, however, ought to stimulate us all to render prompt obedience to God; for Christ is a pattern of perfect obedience for this end, that all who are his may contend with one another in imitating him, that they may together respond to the call of God, and that their life may exemplify this saying, Lo, I come. To the same purpose is what follows, It is written, that is, that we should do the will of God, according to what is said elsewhere, that the end of our election is, to be holy and unblamable in his sight. (Colossians 1:22.)

Then said I - "I the Messiah." Paul applies this directly to Christ, showing that he regarded the passage in the Psalm as referring to him as the speaker.
Lo, I come - Come into the world; Hebrews 10:5. It is not easy to see how this could be applied to David in any circumstance of his life. There was no situation in which he could say that, since sacrifices and offerings were not what was demanded, he came to do the will of God in the place or stead of them. The time here referred to by the word "then" is when it was manifest that sacrifices and offerings for sin would not answer all the purposes desirable, or when in view of that fact the purpose of the Redeemer is conceived as formed to enter upon a work which would effect what they could not.
In the volume of the book it is written of me - The word rendered here "volume " - κεφαλίς kephalis - means properly "a little head;" and then a knob, and here refers doubtless to the head or knob of the rod on which the Hebrew manuscripts were rolled. Books were usually so written as to be rolled up, and when they were read they were unrolled at one end of the manuscript, and rolled up at the other as fast as they were read; see notes on Luke 4:17. The rods on which they were rolled had small heads, either for the purpose of holding them, or for ornament, and hence, the name head came metaphorically to be given to the roll or volume. But what volume is here intended? And where is that written which is here referred to? If David was the author of the Psalm from which this is quoted Ps. 40, then the book or volume which was then in existence must have been principally, if not entirely, the five books of Moses, and perhaps the books of Job, Joshua, and Judges, with probably a few of the Psalm. It is most natural to understand this of the Pentateuch, or the five books of Moses, as the word "volume" at that time would undoubtedly have most naturally suggested that.
But plainly, this could not refer to David himself, for in what part of the Law of Moses, or in any of the volumes then extant, can a reference of this kind be found to David? There is no promise, no intimation that he would come to "do the will of God" with a view to effect what could not be done by the sacrifices prescribed by the Jewish Law. The reference of the language, therefore, must be to the Messiah - to some place where it is represented that he would come to effect by his obedience what could not be done by the sacrifices and offerings under the Law. But still, in the books of Moses, this language is not literally found, and the meaning must be, that this was the language which was there implied respecting the Messiah; or this was the substance of the description given of him, that he would como to take the place of those sacrifices, and by his obedience unto death would accomplish what they could not do.
They had a reference to him; and it was contemplated in their appointment that their inefficiency would be such that there should be felt a necessity for a higher sacrifice, and when he should come they would all be done away. The whole language of the institution of sacrifices, and of the Mosaic economy, was, that a Saviour would hereafter come to do the will of God in making an atonement for the sin of the world. That there are places in the books of Moses which refer to the Saviour, is expressly affirmed by Christ himself John 5:46, and by the apostles (compare Acts 26:22, Acts 26:3), and that the general spirit of the institutions of Moses had reference to him is abundantly demonstrated in this Epistle. The meaning here is, "I come to do thy will in making an atonement, for no other offering would expiate sin. That I would do this is the language of the Scriptures which predict my coming, and of the whole spirit and design of the ancient dispensation."
To do thy will, O God - This expresses the amount of all that the Redeemer came to do. He came to do the will of God:
(1) by perfect obedience to his Law, and,
(2) by making an atonement for sin - becoming "obedient unto death;" Philippians 2:8.
The latter is the principal thought here, for the apostle is showing that sacrifice and offering such as were made under the Law would not put away sin, and that Christ came in contradistinction from them to make a sacrifice that would be efficacious. Everywhere in the Scriptures it is held out as being the "will of God" that such an atonement should be made. There was salvation in no other way, nor was it possible that the race should be saved unless the Redeemer drank that cup of bitter sorrows; see Matthew 26:39. We are not to suppose, however, that it was by mere arbitrary will that those sufferings were demanded. There were good reasons for all that the Saviour was to endure, though those reasons are not all made known to us.

In the volume of the book - במגלת ספר bimgillath sepher, "in the roll of the book." Anciently, books were written on skins and rolled up. Among the Romans these were called volumina, from volvo, I roll; and the Pentateuch, in the Jewish synagogues, is still written in this way. There are two wooden rollers; on one they roll on, on the other they roll off, as they proceed in reading. The book mentioned here must be the Pentateuch, or five books of Moses; for in David's time no other part of Divine revelation had been committed to writing. This whole book speaks about Christ, and his accomplishing the will of God; not only in, The seed of the woman shall bruise the head of the serpent, and, In thy seed shall all the nations of the earth be blessed, but in all the sacrifices and sacrificial rites mentioned in the law.
To do thy will - God willed not the sacrifices under the law, but he willed that a human victim of infinite merit should be offered for the redemption of mankind. That there might be such a victim, a body was prepared for the eternal Logos; and in that body he came to do the will of God, that is, to suffer and die for the sins of the world.

Then said I, lo, I come,.... Christ observing that legal sacrifices were not acceptable to God; that there was a body prepared for him; and that it was written of him in the book of God, that he should come; and the time being now come, with a note of attention and admiration, the matter being of great moment and concern, he cheerfully expresses his readiness to come, immediately, without any compulsion, even he himself, and not another.
In the volume of the book it is written of me; in the book of the law, as the, Targum and Kimchi on Psalm 40:7 interpret it; and which may design the Bible in general, the whole book of the Scriptures of the Old Testament: so "the book", is used for the whole Bible (r), and it is said (s), all the whole law, that is, all Scripture, is called "a volume"; accordingly there are things written of Christ in all the writings of the Old Testament, in the law, and in the prophets, and in the psalms. Jarchi interprets it of the law of Moses, and so it may design the pentateuch, or the five books of Moses; and there are several places therein, in which it is written of Christ, and particularly in Genesis, the first of these books, and in the head, the beginning, the frontal piece, the first part of that book; namely, Genesis 3:15 which may be principally designed. Books were formerly written in rolls of parchment, and hence called volumes; See Gill on Luke 4:17, See Gill on Luke 4:20. The end of his coming is next expressed by him,
to do thy will, O God; which, when he came, he set about with the utmost delight, diligence, and faithfulness, in preaching the Gospel, performing miracles, doing good to the bodies and souls of men, and in finishing the great work of man's redemption, which was the main part of his Father's will he came to do; and which he did, by fulfilling the law in its precept and penalty; by offering himself a sacrifice to God; by suffering death, the death of the cross; by destroying all his and our enemies, and so working out everlasting salvation.
(r) T. Hieros, Megilla, fol. 73. 4. (s) T. Bab. Gittin, fol. 60. 1.

I come--rather, "I am come" (see on Hebrews 10:5). "Here we have the creed, as it were, of Jesus: 'I am come to fulfil the law,' Matthew 5:17; to preach, Mark 1:38; to call sinners to repentance, Luke 5:32; to send a sword and to set men at variance, Matthew 10:34-35; I came down from heaven to do the will of Him that sent me, John 6:38-39 (so here, Psalm 40:7-8); I am sent to the lost sheep of the house of Israel, Matthew 15:24; I am come into this world for judgment, John 9:39; I am come that they might have life, and might have it more abundantly, John 10:10; to save what had been lost, Matthew 18:11; to seek and to save that which was lost, Luke 19:10; compare 1-Timothy 1:15; to save men's lives, Luke 9:56; to send fire on the earth, Luke 12:49; to minister, Matthew 20:28; as "the Light," John 12:46; to bear witness unto the truth, John 18:37. See, reader, that thy Saviour obtain what He aimed at in thy case. Moreover, do thou for thy part say, why thou art come here? Dost thou, then, also, do the will of God? From what time? and in what way?" [BENGEL]. When the two goats on the day of atonement were presented before the Lord, that goat on which the lot of the Lord should fall was to be offered as a sin offering; and that lot was lifted up on high in the hand of the high priest, and then laid upon the head of the goat which was to die; so the hand of God determined all that was done to Christ. Besides the covenant of God with man through Christ's blood, there was another covenant made by the Father with the Son from eternity. The condition was, "If He shall make His soul an offering for sin, He shall see His seed," &c. (Isaiah 53:10). The Son accepted the condition, "Lo, I come to do Thy will, O God" [BISHOP PEARSON]. Oblation, intercession, and benediction, are His three priestly offices.
in the volume, &c.--literally, "the roll": the parchment manuscript being wrapped around a cylinder headed with knobs. Here, the Scripture "volume" meant is the fortieth Psalm. "By this very passage 'written of Me,' I undertake to do Thy will [namely, that I should die for the sins of the world, in order that all who believe may be saved, not by animal sacrifices, Hebrews 10:6, but by My death]." This is the written contract of Messiah (compare Nehemiah 9:38), whereby He engaged to be our surety. So complete is the inspiration of all that is written, so great the authority of the Psalm, that what David says is really what Christ then and there said.

In the volume of the book - In this very psalm it is written of me. Accordingly I come to do thy will - By the sacrifice of myself.