Numbers 8:21

8:21 The Levites purified themselves and washed their clothing; then Aaron presented them like a wave offering before the Lord, and Aaron made atonement for them to purify them.

Numbers 20:26

20:26 Remove Aaron’s priestly garments and put them on Eleazar his son, and Aaron will be gathered to his ancestors and will die there.”

Numbers 20:29

20:29 When all the community saw that Aaron was dead, the whole house of Israel mourned for Aaron thirty days.