Zechariah 11:12-13
English Standard Version (ESV)
Thirty pieces of silver is the price Zechariah got for his work. He takes the coins and throws them “to the potter”. In , 30 pieces of silver was the price of a slave.
When the chief priests decide to buy a field with the returned money, Matthew says that this fulfilled “what was spoken by Jeremiah the prophet.” Namely, “They took the thirty silver coins, the price set on him by the people of Israel, and they used them to buy the potter’s field, as the Lord commanded me” (Matthew 27:9–10).
Jeremiah 32
Exodus 21:32
English Standard Version (ESV)
32 If the ox gores a slave, male or female, the owner shall give to their master thirty shekels of silver, and the ox shall be stoned.
The coins may also be defining “Jesus’ death is a ransom, the price paid to secure a slave’s freedom,” and that the use of the blood money to buy a place to bury the rootless (Matthew 27:7) may hint at the idea that “Jesus’ death makes salvation possible for all the peoples of the world.
There may also be a reference here to the Cain and Abel story where the older brother kills his younger and the bloody field cries out to God.