Numbers 31:3

31:3 So Moses spoke to the people: “Arm men from among you for the war, to attack the Midianites and to execute the Lord’s vengeance on Midian.

Numbers 32:20-21

32:20 Then Moses replied, “If you will do this thing, and if you will arm yourselves for battle before the Lord, 32:21 and if all your armed men cross the Jordan before the Lord until he drives out his enemies from his presence