Psalm 40

"He brought me up also out of an horrible pit, out of the miry clay, and set my feet upon a rock." The pit is a cistern, cut bottle-shaped into limestone and plastered to hold winter rain. When one ran low, the bottom was deep sludge. Jeremiah was let down into exactly such a cistern and sank in the mire, and had to be hauled out with rags under his arms so the ropes would not cut him.

"Mine ears hast thou opened" reads in Hebrew as "ears thou hast dug for me." Some hear an echo of the servant in Exodus who chose to stay with his master for life and had his ear pierced with an awl against the doorpost — a permanent, visible mark of belonging. The Greek translation rendered the line differently, "a body thou hast prepared me," and Hebrews quotes that form; the two readings are both ancient and the difference is worth naming rather than hiding.

"In the volume of the book it is written of me" refers to a scroll — a roll of leather or papyrus sheets sewn together and wound on a stick. Israel's king was commanded to write out his own copy of the Law and read it all his days, so a king speaking of a scroll written about him is speaking of a document he personally owned.

The offerings listed in verse 6 — sacrifice, offering, burnt offering, sin offering — are the four main categories of the altar. The psalm does not abolish them; it says God took no pleasure in them by themselves, which is what the prophets would spend centuries repeating.