en_tn_lite_do_not_use/mat/01/22.md

Matthew quotes a prophecy that the birth of Jesus would fulfill.

what was spoken by the Lord through the prophet

This could be stated in the active voice as "what the Lord told the prophet Isaiah to write long ago." (See: rc://en/ta/man/translate/figs-activepassive)

Behold

Alternative translation: “Look” or “Listen” or “Pay attention to what I am about to tell you.”

the virgin will conceive and give birth to a son

This verse is a direct quotation from Isaiah 7:13.