en_tn/mat/24/15.md

the abomination of desolation, which was spoken of by Daniel the prophet

This can be stated in active form. AT: "the shameful one who defiles the things of God, about whom Daniel the prophet wrote" (See: rc://en/ta/man/translate/figs-activepassive)

let the reader understand

This is not Jesus speaking. Matthew added this to alert the reader that Jesus was using words that they would need to think about and interpret.