Numbers 3:14-20

14And the LORD spoke to Moses in the wilderness of Sinai, saying, 15Number the children of Levi after the house of their fathers, by their families: every male from a month old and upward shalt thou number them. 16And Moses numbered them according to the word of the LORD, as he was commanded.1 17And these were the sons of Levi by their names; Gershon, and Kohath, and Merari. 18And these are the names of the sons of Gershon by their families; Libni, and Shimei. 19And the sons of Kohath by their families; Amram, and Izehar, Hebron, and Uzziel. 20And the sons of Merari by their families; Mahli, and Mushi. These are the families of the Levites according to the house of their fathers.