Of a stranger, i.e. of a strange nation, which the Canaanites possess; for though the city Jerusalem had been taken by Caleb, Jud 1, yet the strong fort of Zion was still in their hands, 2 Samuel 5:6,7, whence it is likely they did much molest, and afterwards, by God's permission, and for the punishment of their sin, drive out the Israelites who dwelt there.
Related Commentaries of Judges 19:12
Judges 19:12
12 And his master said unto him, We will not turn aside hither into the city of a stranger, that is not of the children of Israel; we will pass over to Gibeah.