what was spoken through Jeremiah the prophet was fulfilled: The quote is from Zechariah 11:12–13. Matthew might have followed the Jewish tradition of naming books by the first book in the scroll. In this case, Jeremiah would be the first book in the scroll containing Zechariah. Or, Matthew might be referencing similar passages in Jeremiah (Jeremiah 19:1–13; 18:2–6; 32:6–15) along with Zechariah 11:12–13.
Matthew notices a strong similarity between Zechariah's actions and those of the leading priests. Both situations involve rejecting God's messenger, who was meant to be the king of God's people.