That came not up with the congregation When summoned to come together under a great penalty upon those who absented themselves. For they had made a great oath That is, a solemn oath, joined with some terrible execration against the offenders herein. This oath probably was made by the great assembly of their rulers (called the whole congregation) when they summoned the people to Mizpeh, as the other oath (mentioned Jdg 21:1) was made after the people were come thither, upon the Benjamites' refusal to do justice. He shall surely be put to death Because, by refusing to execute the vengeance due to such malefactors, they were presumed to be guilty of the crime, and therefore liable to the same punishment, as was the case of that city that would not deliver up an idolater, dwelling among them, to justice.
Related Commentaries of Judges 21:5
Judges 21:5
5 And the children of Israel said, Who is there among all the tribes of Israel that came not up with the congregation unto the LORD? For they had made a great oath concerning him that came not up to the LORD to Mizpeh, saying, He shall surely be put to death.