Numbers 31:2-4

Young's Literal Translation

² `Execute the vengeance of the sons of Israel against the Midianites -- afterwards thou art gathered unto thy people.'

³ And Moses speaketh unto the people, saying, `Be ye armed some of you for the host, and they are against Midian, to put the vengeance of Jehovah on Midian;

⁴ a thousand for a tribe -- a thousand for a tribe, to all the tribes of Israel -- ye do send to the host.'