Numbers 3:2-10

These are the names of Aaron’s sons: Nadab, the firstborn, and Abihu, Eleazar, and Ithamar. These are the names of Aaron’s sons, the anointed priests, who were ordained to serve as priests. But Nadab and Abihu died in the LORD’s presence when they presented unauthorized fire  before the LORD in the Wilderness of Sinai, and they had no sons. So Eleazar and Ithamar served as priests under the direction of Aaron their father.  The LORD spoke to Moses: “Bring the tribe of Levi near and present them to the priest Aaron to assist him. They are to perform duties for  him and the entire community before the tent of meeting by attending to the service of the tabernacle. They are to take care of all the furnishings of the tent of meeting  and perform duties for the Israelites by attending to the service of the tabernacle. Assign the Levites to Aaron and his sons; they have been assigned exclusively to him  from the Israelites.  You are to appoint Aaron and his sons to carry out their priestly responsibilities, but any unauthorized person who comes near the sanctuary is to be put to death.”