Numbers 31:5 DBY

³  And Moses spoke to the people, saying, Arm from amongst you men for military service, that they go against Midian to execute Jehovah's vengeance upon Midian.

⁴  Of every tribe a thousand, of all the tribes of Israel, shall ye send to the war.

⁵  And there were levied out of the thousands of Israel, a thousand by tribe, twelve thousand armed for war.

⁶  And Moses sent them to the war, a thousand by the tribe, them and Phinehas the son of Eleazar the priest, to the war, and the holy instruments, even the alarm-trumpets in his hand.

⁷  And they warred against Midian, as Jehovah had commanded Moses, and slew all the males.