Numbers 30:2

30:2 When a man vows a vow to Yahweh, or swears an oath to bind his soul with a bond, he shall not break his word; he shall do according to all that proceeds out of his mouth.
-World English Bible

Other Translation

30:2 If a man vow a vow unto the LORD, or swear an oath to bind his soul with a bond; he shall not break his word, he shall do according to all that proceedeth out of his mouth.
-King James Version