But now this is the thing which we will do to Gibeah: [we will go up] against it by lot;
By casting lots to see how they should proceed against Benjamin (Judges 20:9), the tribes were dealing with Benjamin as they had dealt with the Canaanite towns they had attacked. God did not tell them to deal with their fellow Israelites this way (cf. Deuteronomy 13:12-18). They were now battling their brethren as they had engaged their enemies (Judges 20:18; cf. Leviticus 19:18).