God Commanded Moses To Take A Census, Numbers 1...

Now the Lord spoke to Moses in the Wilderness of Sinai, in the tabernacle of meeting, on the first day of the second month, in the second year after they had come out of the land of Egypt, saying: “Take a census of all the congregation of the children of Israel, by their families, by their fathers’ houses, according to the number of names, every male individually, from twenty years old and above—all who are able to go to war in Israel. You and Aaron shall number them by their armies. And with you there shall be a man from every tribe, each one the head of his father’s house. These are the ones who were numbered of the children of Israel by their fathers’ houses. All who were numbered according to their armies of the forces were six hundred and three thousand five hundred and fifty. But the Levites were not numbered among the children of Israel, just as the Lord commanded Moses. Thus the children of Israel did according to all that the Lord commanded Moses; so they camped by their standards and so they broke camp, each one by his family, according to their fathers’ houses.
Numbers 1:1-4,2:32-34 - hNKJV