Numbers 31:2-4

Revised Standard Version

² “Avenge the people of Israel on the Mid′ianites; afterward you shall be gathered to your people.” ³ And Moses said to the people, “Arm men from among you for the war, that they may go against Mid′ian, to execute the Lord’s vengeance on Mid′ian. ⁴ You shall send a thousand from each of the tribes of Israel to the war.”