"I have heard you say many times that the Bible does not contradict itself. Now Matthew 27:9 is supposedly a prophecy from Jeremiah. Yet it cannot be found in Jeremiah. How would you explain that?" Many carelessly assume that Matthew 27:9 is quoted from Jeremiah. Let's not assume! Read this scripture and see what it actually states.
Matthew, under inspiration, wrote: "Then was fulfilled that which was SPOKEN by Jeremy (Jeremiah) the prophet, saying, And they took the thirty pieces of silver, the price of him that was valued, whom they of the children of Israel did value" (Matt. 27:9).
Notice! the Prophecy was SPOKEN, written, by Jeremiah!
Some so-called "higher critics" say the word Jeremiah should be amended to read Zechariah, as this prophecy is found written in Zechariah 11:13. This is not so! The original Greek used here is, in all authoritative texts, Jeremiah, not Zechariah.
The answer is simple!
Jeremiah spoke a prophecy. Zechariah, writing at a later time, was inspired by the Holy Spirit to write this prophecy as a part of the very Word of God.
If only people would believe what is written and not reason their way around it, they would plainly see the Bible doesn't contradict itself. "The scripture cannot be broken" (John 10:35).