In the Judges 19:1–20:48 narrative, particularly in the battles recorded in the previous chapter, Israel repeatedly went back to the Lord, with tears, and with questions, Shall we again fight against our brothers?
The same thing is happening now, after the final battle against Benjamin. Except here Israel’s question is something they could better ask themselves, since they made the vow.
3 And they said, “O LORD, the God of Israel, why has this happened in Israel, that today there should be one tribe lacking in Israel?”