John Trapp on Psalms 40:7

Verſ. 7. Then ſaid I, Lo I come] Chriſt became obedient even to the death, yea that of the Croſs, Phil. 2.8. Chriſts people alſo are a willing people, Pſal. 110.3. their obedience is prompt, and preſent, ready, and ſpeedy, without delays and conſults, Pſal. 119.60. without capitulation and ſecurity, Iſa. 56.6.

In the volume of thy book] In libre plicatili, in thy Law which was anciently, (and is till this day amongſt the Jews) written in Paper, or Parchment rolled up; becauſe it will laſt longer rolled than folded.

It is written of me] Of Chriſt, in many places: for He is both Author, Object, Matter, and Mark of both Teſtaments. Of David alſo, and all Gods people, doth the Law ſpeak with fruit and efficacy; and they do uſe to read their own names, written as it were in every precept, promiſe, threatning. Look how men read the Statute-book of the Land, as holding themſelves highly concerned therein; So here.