Judges 20:27-31

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.

And the sons of Israel went up against the sons of Benjamin on the third day and lined up against Gibeah as at other times.

When the sons of Benjamin went out against the people, they were lured away from the city, and they began to strike and kill some of the people as at other times, on the roads (one of which goes up to Bethel, and the other to Gibeah), and in the field, about thirty men of Israel.