Hebrews 10:5

Wherefore when he cometh into the world he saith, Sacrifice and offering thou wouldest not, But a body didst thou prepare for me; In whole burnt offerings and sacrifices for sins thou hadst no pleasure: Then said I, Lo, I come (In the roll of the book it is written of me) To do thy will, O God.

This quotation from Psalms 40:6-8 is introduced by the words, "When he cometh into the world," a reference to the incarnation of Christ, making him the true author of the words of David in this Psalm, and requiring that these words be understood as spoken by the Lord Jesus Christ and not by David. Lenski was doubtless correct in his understanding of this remarkable prophecy. He said:

The great force which these lines of the psalm and this true analysis of what they say has for the readers lies in the fact that David has written these lines in the psalm; they are in the holy scriptures, are a part of all that David the type says for the antitype, the Messiah. The lines are the voice of the Messiah himself speaking to God hundreds of years before this Messiah "appeared" (26) and did God's will.[7]

Also, from the comment of Westcott, "The words, it will be observed, assume the pre-existence of Christ."[8]

The well known problem of this place is that the author of Hebrews apparently quoted from the Septuagint (LXX) version of the Scriptures which differs greatly from the Hebrew text in the key words about the preparation of a body for the Messiah. Of this, Thomas said:

The Hebrew reads, "Mine ears thou hast opened," while the Greek text from which the quotation is made reads, "A body hast thou prepared me." On the principle that the Greek reading is the harder, it may be regarded as the original.[9]

We shall presume to pass no judgment as to the relative value of the word of scholars on this difficulty; but we do confidently affirm the right of every believer to accept the words as here quoted to be authentic and faithful words of God, reported in the verses before us by the inspired author of Hebrews.

Sacrifice and offering ... whole burnt offerings and sacrifices for sins, constitute two pairs of words regarding the Jewish sacrifices, and again to Westcott we are indebted for this instructive note:

The two pairs of words give a complete view of the Jewish sacrifices. The first two describe them according to their material, the animal offering, and the meal offering. The second pair give in the burnt offering and the sin offering, representative types of the two great classes of offerings.[10]

In the roll of the book it is written of me seems like a strange expression; but as Clarke said,

Anciently, books were written on skins 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 the one they roll ON; on the other they roll OFF.[11]

Clark also pinpointed the identification of just which book is meant, in these words,

The book mentioned here must be the Pentateuch, 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 Genesis 3:15, but in all the sacrifices and sacrificial rites mentioned in the law.[12]

The statement of the Messiah in presenting himself to do God's will, before his incarnation and at the time God purposed the redemptive act on behalf of man, is as follows; "Lo, I come to do thy will, O God." All kinds of offerings and sacrifices having failed to please God, or to give him any pleasure, and failing totally to remove man's sin and restore his broken fellowship with God, Christ in this place appears as the great Volunteer who would undertake the task. Even he would not be able to do it with such things as animal sacrifices, but would need "a body," a body prepared of God and made available to the Messiah through the seed of David; thus the principle is established that absolutely nothing less than the death of man for the sins of man could prevail; and no ordinary sinful man would suffice for such a purpose. Nothing less than the perfect and sinless Son of God could avail to make atonement.

No angel could his place have taken, Highest of the High, though he; The loved One on the cross forsaken Was one of the Godhead three.[13]

Thus, the dramatic and world-shaking significance of Christ's voluntary assumption of so dreadful and necessary a task on man's behalf is seen in the words, "Lo, I come to do thy will, O God." How profoundly different was the voluntary work of Christ from that of the old law offerings, which were not the result of any willing or voluntary assent on the part of the victims, but depended upon the arbitrary selection of others. How these precious words glow upon the sacred page: "Lo, I come to do thy will, O God"!