Numbers 26:2-4

ISV(i) 2 “Take a census of the entire community of Israel from the age of 20 years and above, according to each ancestral tribe, counting everyone who is able to go out to war in Israel.”
3 Moses and Eleazar the priest spoke to them in the plains of Moab, by the Jordan River in Jericho. 4 They counted every male Israeli who had come out of Egypt and who was 20 years old and above, just as the LORD had commanded Moses.