en_tn/act/01/16.md

it was necessary that the scripture should be fulfilled

This can be stated in active form. Alternate translation: "the things that we read about in scripture had to take place" (See: rc://en/ta/man/translate/figs-activepassive)

by the mouth of David

The word "mouth" refers to the words that David wrote. Alternate translation: "through the words of David" (See: rc://en/ta/man/translate/figs-metonymy)