Numbers 18:15

“Sanctify to Me every firstborn, the first offspring of every womb among the sons of Israel, both of man and beast; it belongs to Me.”

and you shall devote to Yahweh the first offspring of every womb and the first offspring of every beast that you own; the males belong to Yahweh.

“But every first offspring of a donkey you shall redeem with a lamb, but if you do not redeem it, then you shall break its neck; and every firstborn of man among your sons you shall redeem.

“For the redemption price of the 273 of the firstborn of the sons of Israel who are in excess beyond the Levites,

Do you not know that those who perform sacred services eat the food of the temple, and those who attend regularly to the altar have their share from the altar?