General Information:

Christ's words when he was on earth were foretold in this quotation from a psalm of David.

that you desired

Here "you" is singular and refers to God. (See: rc://en/ta/man/translate/figs-you)

"made ready"

Here "I" refers to Christ.

This can be stated in active form. AT: "as the prophets wrote about me in the scroll" (See: rc://en/ta/man/translate/figs-activepassive)

This means the scriptures or the holy writings.