9 They are assigned to help Aaron and his sons,
10 who have been appointed to be priests. Anyone else who tries to perform the duties of a priest must be put to death.
11-13 Moses, I have chosen these Levites from all Israel, and they will belong to me in a special way. When I killed the first-born sons of the Egyptians, I decided that the first-born sons in every Israelite family and the first-born males of their flocks and herds would be mine. But now I accept these Levites in place of the first-born sons of the Israelites.
14 In the Sinai Desert the Lord said to Moses,
15 “Now I want you to count the men and boys in the Levi tribe by families and by clans. Include every one at least a month old.”
16 So Moses obeyed and counted them.
17 Levi's three sons, Gershon, Kohath, and Merari, had become the heads of their own clans.