Numbers 31:3-5

King James Version

³ And Moses spake unto the people, saying, Arm some of yourselves unto the war, and let them go against the Midianites, and avenge the Lord of Midian.

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

⁵ So there were delivered out of the thousands of Israel, a thousand of every tribe, twelve thousand armed for war.