Numbers 33:39

37They traveled from Kadesh, and encamped in Mount Hor, in the edge of the land of Edom.

38Aaron the priest went up into Mount Hor at the commandment of the LORD and died there, in the fortieth year after the children of Israel had come out of the land of Egypt, in the fifth month, on the first day of the month.

39Aaron was one hundred twenty-three years old when he died in Mount Hor.

40The Canaanite king of Arad, who lived in the South in the land of Canaan, heard of the coming of the children of Israel.

41They traveled from Mount Hor, and encamped in Zalmonah.