Numbers 33:37-39

37They journeyed from Kadesh and camped at 1Mount Hor, 2at the edge of the land of Edom.

383Then Aaron the priest went up to Mount Hor at the 4command of the Lord, and died there in the fortieth year after the sons of Israel had come from the land of Egypt, on the first day in the fifth month. 39Aaron was one hundred twenty-three years old when he died on Mount Hor.