Numbers 31:2-4

Darby Translation

² Avenge the children of Israel upon the Midianites; afterwards shalt thou be gathered unto thy peoples.

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.