When you shall vow a vow to the LORD your God, you shall not slack to pay it: for the LORD your God will surely require it of you; and it would be sin in you.
That which is gone out of your lips you shall keep and perform; even a freewill offering, according as you have vowed to the LORD your God, which you have promised with your mouth.
And the children of Israel smote them not, because the princes of the congregation had sworn to them by the LORD God of Israel. And all the congregation murmured against the princes.