Numbers 31:3-5

Darby Translation

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.