The Gospel of Matthew and the Book of Acts say different things about his death. Why is this not a contradiction in the Bible?
Matthew 27:3-7 NIV
When Judas, who had betrayed him, saw that Jesus was condemned, he was seized with remorse and returned the thirty pieces of silver to the chief priests and the elders. “I have sinned,” he said, “for I have betrayed innocent blood.”
“What is that to us?” they replied. “That’s your responsibility.”
So Judas threw the money into the temple and left. Then he went away and hanged himself.
The chief priests picked up the coins and said, “It is against the law to put this into the treasury, since it is blood money.” So they decided to use the money to buy the potter’s field as a burial place for foreigners.
Acts 1:18 New International Version NIV
With the payment he received for his wickedness, Judas bought a field; there he fell headlong, his body burst open and all his intestines spilled out.
Augustine of Hippo (Saint Augustine in Orthodox tradition) seems to be the first major commentator to establish that these texts are simply describing different aspects of the same events. The priests purchased the field with the blood money earned by Judas, as if they were acting as his agents. A potter's field would be littered with broken pottery and unsuitable for farming.
Judas went to an isolated place, tied his neck to a tree over-looking the same field, and stepped out into the air. His body decomposed until the rope or branch gave way, leading to the ignominious fall and bursting.