Numbers 33:38

33:38 Aaron the priest went up into Mount Hor at the commandment of Yahweh, and died there, in the fortieth year after the children of Israel were come out of the land of Egypt, in the fifth month, on the first day of the month.
-World English Bible

Other Translation

33:38 And Aaron 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 were come out of the land of Egypt, in the first [day] of the fifth month.
-King James Version