Solemn voluntary promises made to God, often in the context of distress or thanksgiving, binding once made. Vows are not commanded (Deut 23:22: if thou shalt forbear to vow, it shall be no sin in thee) but obligatory once spoken. Numbers 30 details the law of vows (including father's and husband's authority to disallow a woman's vow). Ecclesiastes 5:4-5: When thou vowest a vow unto God, defer not to pay it; for he hath no pleasure in fools: pay that which thou hast vowed. Better is it that thou shouldest not vow, than that thou shouldest vow and not pay. Christ's caution in Matthew 5:33-37 raises the bar further: rather than negotiating oath categories, let your yes be yes and your no be no. The biblical man uses vows sparingly but treats them with full seriousness when made — marriage vows, baptismal vows, ordination vows, and any explicit promise made before God.