Deuteronomy 18:3-5

New International Reader's Version

³ Anyone who sacrifices a bull or a sheep owes a share of it to the priests. Their share is the shoulder, the inside parts and the meat from the head. ⁴ You must give the priests the first share of the harvest of your grain, olive oil and fresh wine. You must also give them the first wool you clip from your sheep. ⁵ The Lord your God has chosen the Levites and their sons after them to serve him in his name always. He hasn’t chosen priests from any of your other tribes.