Numbers 20:25–29

25 Take Aaron and his son Eleazar and bring them up Mount Hor. 26 Remove Aaron’s garments and put them on his son Eleazar. Aaron will be gathered to his people and die there.”

27 So Moses did as the Lord commanded, and they climbed Mount Hor in the sight of the whole community. 28 After Moses removed Aaron’s garments and put them on his son Eleazar, Aaron died there on top of the mountain. Then Moses and Eleazar came down from the mountain. 29 When the whole community saw that Aaron had passed away, the entire house of Israel mourned for him thirty days.