1This is the lineage of Aaron and Moses at the time when the LORD spoke with Moses on Mount Sinai. 2These are the names of the sons of Aaron: Nadab the firstborn, and Abihu, Eleazar, and Ithamar; 3these are the names of the sons of Aaron, the anointed priests, whom he ordained to minister as priests. 4Nadab and Abihu died before the LORD when they offered illicit fire before the LORD in the wilderness of Sinai, and they had no children. Eleazar and Ithamar served as priests in the lifetime of their father Aaron.
5Then the LORD spoke to Moses, saying: 6Bring the tribe of Levi near, and set them before Aaron the priest, so that they may assist him. 7They shall perform duties for him and for the whole congregation in front of the tent of meeting, doing service at the tabernacle; 8they shall be in charge of all the furnishings of the tent of meeting, and attend to the duties for the Israelites as they do service at the tabernacle. 9You shall give the Levites to Aaron and his descendants; they are unreservedly given to him from among the Israelites. 10But you shall make a register of Aaron and his descendants; it is they who shall attend to the priesthood, and any outsider who comes near shall be put to death.
11Then the LORD spoke to Moses, saying: 12I hereby accept the Levites from among the Israelites as substitutes for all the firstborn that open the womb among the Israelites. The Levites shall be mine, 13for all the firstborn are mine; when I killed all the firstborn in the land of Egypt, I consecrated for my own all the firstborn in Israel, both human and animal; they shall be mine. I am the LORD.