Numbers 3:15

3:15 “Number the Levites by their clans and their families; every male from a month old and upward you are to number.”

Numbers 3:20

3:20 The sons of Merari by their families were Mahli and Mushi. These are the families of the Levites by their clans.

Numbers 4:46

4:46 All who were numbered of the Levites, whom Moses, Aaron, and the leaders of Israel numbered by their families and by their clans,

Numbers 26:2

26:2 “Take a census of the whole community of Israelites, from twenty years old and upward, by their clans, everyone who can serve in the army of Israel.”