Judges 20:25-29

And Benjamin went out against them from Gibeah the second day and struck to the ground again eighteen thousand men of the sons of Israel; all of these drew the sword.

Then all the sons of Israel and all the people went up and came to Bethel, and they wept and remained there before the Lord, and fasted that day until evening. And they offered burnt offerings and peace offerings before the Lord.

And the sons of Israel inquired of the Lord (for the ark of the covenant of God was there in those days,

and Phinehas the son of Eleazar, Aaron’s son, stood before it to minister in those days), saying, “Shall I yet again go out to battle against the sons of my brother Benjamin, or shall I stop?” And the Lord said, “Go up, for tomorrow I will hand them over to you.”

So Israel set men in ambush around Gibeah.