Deuteronomy 23:21-23 - Keeping Vows
21 "{When you make a vow} to Yahweh your God, you shall not postpone {fulfillment of it}, [for] certainly Yahweh your God shall require it from you and [if postponed] {you will incur guilt}. 22 And {if you refrain from vowing}, {you shall not incur guilt}. 23 The utterance of your lips {you must perform diligently} [just] as you have vowed freely to Yahweh your God whatever [it was] that you promised with your mouth.