Numbers 1:53

"And Moses said unto Aaron, Take a censer, and put fire therein from off the altar, and put on incense, and go quickly unto the congregation, and make an atonement for them: for there is wrath gone out from the LORD; the plague is begun."

"And that they should keep the charge of the tabernacle of the congregation, and the charge of the holy place, and the charge of the sons of Aaron their brethren, in the service of the house of the LORD."

"And Moses said unto Aaron, and unto Eleazar and unto Ithamar, his sons, Uncover not your heads, neither rend your clothes; lest ye die, and lest wrath come upon all the people: but let your brethren, the whole house of Israel, bewail the burning which the LORD hath kindled."

"And of the children of Israel's half, thou shalt take one portion of fifty, of the persons, of the beeves, of the asses, and of the flocks, of all manner of beasts, and give them unto the Levites, which keep the charge of the tabernacle of the LORD."

"Even of the children of Israel's half, Moses took one portion of fifty, both of man and of beast, and gave them unto the Levites, which kept the charge of the tabernacle of the LORD; as the LORD commanded Moses."

"And I have given the Levites as a gift to Aaron and to his sons from among the children of Israel, to do the service of the children of Israel in the tabernacle of the congregation, and to make an atonement for the children of Israel: that there be no plague among the children of Israel, when the children of Israel come nigh unto the sanctuary."

"But as for us, the LORD is our God, and we have not forsaken him; and the priests, which minister unto the LORD, are the sons of Aaron, and the Levites wait upon their business:"