Numbers 30:2

2 When a man vows a vow unto the LORD or swears an oath to bind his soul with a bond, he shall not defile his word: he shall do according to all that proceeded out of his mouth.

Numbers 30:2 In-Context

1 And Moses spoke unto the princes of the tribes concerning the sons of Israel, saying, This is the thing which the LORD has commanded.
2 When a man vows a vow unto the LORD or swears an oath to bind his soul with a bond, he shall not defile his word: he shall do according to all that proceeded out of his mouth.
3 But the woman, when she shall vow a vow unto the LORD and bind herself by a bond, being in her father’s house in her youth,
4 and her father hears her vow and her bond with which she has bound her soul, and her father shall remain silent regarding it, then all her promises shall stand, and every bond with which she has bound her soul shall stand.
5 But if her father disallows her in the day that he hears all of her vows and of her bonds with which she has bound her soul, they shall not stand, and the LORD shall forgive her, because her father disallowed her.
The Jubilee Bible (from the Scriptures of the Reformation), edited by Russell M. Stendal, Copyright © 2000, 2001, 2010