Numbers 1:1-2

1 And the LORD spoke to Moses in the wilderness of Sinai, in the tabernacle of the congregation, on the first [day] of the second month, in the second year after they had come out of the land of Egypt, saying,

2 Take the sum of all the congregation of the sons of Israel, according to their families, by their fathers' house, with the number of names, every male by their heads,