The Hebrew nadar (H5087) means to make a vow β a solemn, sacred pledge to God, typically conditional ('if you do this, I will do that') or dedicatory. Jacob vowed at Bethel (Genesis 28:20-22); Hannah vowed if God gave her a son (1 Samuel 1:11); Jephthah made a rash vow (Judges 11:30-31). Numbers 30:2 establishes the principle: 'When a man makes a vow (nadar) to the LORD or takes an oath to obligate himself by a pledge, he must not break his word.'
The theology of nadar is about the weight of words before God. Ecclesiastes 5:4-5 warns: 'When you make a vow to God, do not delay to fulfill it... It is better not to make a vow than to make one and not fulfill it.' The NT does not abolish vowing (Paul takes a vow in Acts 18:18) but elevates the standard: Jesus teaches that all speech should carry the gravity of a vow β All you need to say is simply Yes or No (Matthew 5:37). The highest vow in Scripture is God's own oath, which grounds the new covenant in absolute certainty (Hebrews 6:17-18).