Números 33:38

38 At the Lord's command Aaron the priest went up Mount Hor, where he died on the first day of the fifth month of the fortieth year after the Israelites came out of Egypt.

38 And Aaron the priest went up into the mountain at the order of the Lord, and came to his death 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.