Numbers 31:3-6

3Moses spoke to the people, saying, “Arm men from among you for the war, that they may 1go against Midian to execute 2the Lord’s vengeance on Midian.

4A thousand from each tribe of all the tribes of Israel you shall send to the war.”

5So there were 3furnished from the thousands of Israel, a thousand from each tribe, twelve thousand armed for war.

6Moses sent them, a thousand from each tribe, to the war, and Phinehas the son of Eleazar the priest, to the war with them, 4and the holy vessels and 5the trumpets for the alarm in his hand.