Verses 1-17
This Ps. falls into two well-marked divisions, which many think to have been originally separate Pss. In Psalms 40:1-11 the writer recalls with thankfulness how God has heard his prayers and delivered him from trouble (Psalms 40:1-4), declares the greatness of God's mercies (Psalms 40:5), presents himself as a living sacrifice (Psalms 40:6-8), and desires the continuance of God's blessing on account of his fearless witness for righteousness (Psalms 40:9-11). In Psalms 40:12-17, on the other hand, the Psalmist is in distress, both from sin (Psalms 40:12) and from persecution (Psalms 40:14-15). He pleads for the speedy confusion of his enemies, and for the deliverance both of himself and of all who seek God (Psalms 40:13-17). This part of the Ps. resembles Psalms 35. Psalms 40:13-17 are reproduced with some variations as Psalms 70. Psalms 40:6-7 are applied to Christ in Hebrews 10:5-9. The Ps. is probably a national Psalm. In it the nation, or the church, rather than the individual, is speaking. The horrible pit will then be the pit of exile, and the new song will be that sung for deliverance from exile and restitution to the home-land. This is one of the Pss. for Good Friday.
2. Pit.. clay] The combination of these figures for trouble is illustrated by the dungeon, with mire at the bottom, into which Jeremiah was cast (Jeremiah 38:6). A rock] a place of firmness and security.
3. A new song] a song of praise for new mercies: see on Psalms 33:3.
6. Sacrifice and offering, etc.] a striking recognition that spiritual service, even in OT. times, is more than all forms of worship: see 1 Samuel 15:22. Mine ears hast thou opened] to understand the true requirements of the Law. The boring of the ears in token of perpetual servitude (Exodus 21:6; Deuteronomy 15:7) is not here referred to. LXX has, 'a body hast thou prepared me,' and is followed in the quotation in Hebrews 10:5.
7. RV 'Lo, I am come,' the Psalmist's personal consecration to God's service: see Isaiah 6:9. In the volume of the book it is written of me] rather, 'in the roll of the book it is prescribed to me.' The words are a parenthesis, and the reference is probably to Deuteronomy (see 2 Kings 22:8.), with its spiritual and inward view of obedience. The writer to the Hebrews rightly recognises that Christ's obedience perfectly fulfilled this ideal of devoted surrender to God's will.
9. In the great congregation] among the people assembled at some festival.
10. Have not hid, etc.] In a good sense God's law is hidden in his heart (Psalms 40:8, cp. Psalms 119:11), but here he means that he has not concealed his convictions from cowardice.