Numbers 30:2

If a man makes a vow to the Lord or swears an oath to obligate himself by a pledge, he must not break his word; he must do everything he has promised.

Note Cited in Matthew 5:33

BSB · Berean Standard Bible
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.

Note break: Heb. profane

KJV · King James Version
When a man vows a vow to the Lord, 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.
WEB · World English Bible
When a man voweth a vow unto Jehovah, or sweareth 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.
ASV · American Standard Version

Related passages

From the Treasury of Scripture Knowledge, grouped by the word they explain.

vow a vow
Numbers 21:2; Genesis 28:20–22; Leviticus 27:2–34; Deuteronomy 23:21, 22; Judges 11:11, 30, 31, 35, 36; Judges 11:39; Psalm 15:3; Psalm 56:12; Psalm 76:11; Psalm 119:106; Proverbs 20:25
swear
Exodus 20:7; Leviticus 5:4; Matthew 5:33, 34; Matthew 14:7–9; Acts 23:12; 2 Corinthians 1:23; 2 Corinthians 9:9–11
to bind
Numbers 30:3, 4, 10; Matthew 23:16, 18; Acts 23:12, 14, 21
break
Heb. profane.
Psalm 55:20
he shall do
Job 22:27; Psalm 22:25; Psalm 50:14; Psalm 66:13, 14; Psalm 116:14, 18; Ecclesiastes 5:4, 5; Nahum 1:15