“Matthew says the chief priests took the money Judas cast down in the temple and bought the ‘field of blood.’ Peter, in Acts, says that Judas bought the field with the ‘reward of iniquity.’ On the surface, this appears to be a contradiction.”
First and foremost, the Word of God never contradicts itself. When there is an apparent contradiction, the problem is not with the Scriptures, but with our understanding of them. Most times the conundrum is easily resolved, which is the case here. However, when we are confronted with no suitable explanation; we simply have to wait on further light before we attempt to interpret a passage.
When the chief priests and elders refused to receive the thirty pieces of silver, as noted, Judas cast them to the floor and went out and hanged himself. After his departure, these religious leaders counseled together as to what to do with the money. Since these ill-gotten funds were used to betray innocent blood, they determined that it would be unlawful to put it into the temple treasury. An honorable thing, indeed, for men who only a few hours earlier were guilty of conspiracy.
So these unscrupulous leaders took Judas’ thirty pieces of silver, “and bought with them the potter’s field, to bury strangers in” (Matt. 27:3-10). Since it was Judas’s money that was used to buy the field, he is credited with the purchase. Peter confirms this when he said, “Now this man [Judas] purchased a field with the reward of iniquity” (Acts 1:18). source