Numbers 3:9

for they are wholly given to Me from among the sons of Israel. I have taken them for Myself instead of every first issue of the womb, the firstborn of all the sons of Israel.

“And I have given the Levites as a gift to Aaron and to his sons from among the sons of Israel, to perform the service of the sons of Israel at the tent of meeting and to make atonement on behalf of the sons of Israel, so that there will be no plague among the sons of Israel by their coming near to the sanctuary.”

is it not enough for you that the God of Israel has separated you from the rest of the congregation of Israel, to bring you near to Himself, to perform the service of the tabernacle of Yahweh, and to stand before the congregation to minister to them;

“But bring near with you also your brothers, the tribe of Levi, the tribe of your father, that they may be joined with you and minister to you, while you and your sons with you are before the tent of the testimony.

“And behold, I Myself have taken your brothers the Levites from among the sons of Israel; they are a gift to you, given to Yahweh, to perform the service for the tent of meeting.

Thus they shall keep responsibility of the tent of meeting, and responsibility of the holy place, and responsibility of the sons of Aaron their relatives, for the service of the house of Yahweh.

and the Levitical priests shall not have a man cut off from before Me who is to offer burnt offerings, to offer up grain offerings in smoke, and to perform sacrifices continually.’”

“Yet they shall be ministers in My sanctuary, having oversight at the gates of the house and ministering in the house; they shall slaughter the burnt offering and the sacrifice for the people, and they shall stand before them to minister to them.