Hebrews 2:17

2:17 Therefore he had to be made like his brothers and sisters in every respect, so that he could become a merciful and faithful high priest in things relating to God, to make atonement for the sins of the people.

Numbers 16:46-48

16:46 Then Moses said to Aaron, “Take the censer, put burning coals from the altar in it, place incense on it, and go quickly into the assembly and make atonement for them, for wrath has gone out from the Lord – the plague has begun!” 16:47 So Aaron did as Moses commanded and ran into the middle of the assembly, where the plague was just beginning among the people. So he placed incense on the coals and made atonement for the people. 16:48 He stood between the dead and the living, and the plague was stopped.

Numbers 18:1-3

Responsibilities of the Priests

18:1 The Lord said to Aaron, “You and your sons and your tribe with you must bear the iniquity of the sanctuary, and you and your sons with you must bear the iniquity of your priesthood.

18:2 “Bring with you your brothers, the tribe of Levi, the tribe of your father, so that they may join with you and minister to you while you and your sons with you are before the tent of the testimony. 18:3 They must be responsible to care for you and to care for the entire tabernacle. However, they must not come near the furnishings of the sanctuary and the altar, or both they and you will die.