Numbers 20:22-29

Now when they set out from Kadesh, the Israelites, the whole congregation, came to Mount Hor. Then the LORD spoke to Moses and Aaron at Mount Hor, by the border of the land of Edom, saying, “Aaron will be gathered to his people [in death]; for he shall not enter the land which I have given to the children of Israel, because you [both] rebelled against My command at the waters of Meribah. [Num 20:7-12] Take Aaron and Eleazar his son and bring them up to Mount Hor; and strip Aaron of his garments and put them on Eleazar his son. So Aaron will be gathered to his fathers, and will die there.” So Moses did just as the LORD had commanded; and they went up Mount Hor in the sight of all the congregation. After Moses stripped Aaron of his [priestly] garments and put them on Eleazar his son, Aaron died there on the mountain top. Then Moses and Eleazar came down from the mountain. When all the congregation saw that Aaron had died, all the house of Israel wept (mourned) for him thirty days.