'Oath' in the Bible

Then the sons of Israel said, “Which one from all the tribes of Israel did not come up in the assembly to the Lord?” For they had taken a great oath concerning him who did not come up to the Lord at Mizpah, saying, “He shall certainly be put to death.”

When their fathers or their brothers come to complain to us, we shall say to them, ‘Give them to us voluntarily, because we did not take a wife for each man of Benjamin in battle, nor did you give wives to them, for that would have made you guilty [of breaking your oath].’”