2 If a man makes a vow to the Lord, or swears an oath to bind himself by some agreement, he shall not break his word; he shall do according to all that proceeds out of his mouth.

3 "Or if a woman makes a vow to the Lord, and binds herself by some agreement while in her father's house in her youth, 4 and her father hears her vow and the agreement by which she has bound herself, and her father holds his peace, then all her vows shall stand, and every agreement with which she has bound herself shall stand. 5 But if her father overrules her on the day that he hears, then none of her vows nor her agreements by which she has bound herself shall stand; and the Lord will release her, because her father overruled her. 6 "If indeed she takes a husband, while bound by her vows or by a rash utterance from her lips by which she bound herself, 7 and her husband hears it, and makes no response to her on the day that he hears, then her vows shall stand, and her agreements by which she bound herself shall stand. 8 But if her husband overrules her on the day that he hears it, he shall make void her vow which she took and what she uttered with her lips, by which she bound herself, and the Lord will release her. 9 "Also any vow of a widow or a divorced woman, by which she has bound herself, shall stand against her. 10 "If she vowed in her husband's house, or bound herself by an agreement with an oath, 11 and her husband heard it, and made no response to her and did not overrule her, then all her vows shall stand, and every agreement by which she bound herself shall stand. 12 But if her husband truly made them void on the day he heard them, then whatever proceeded from her lips concerning her vows or concerning the agreement binding her, it shall not stand; her husband has made them void, and the Lord will release her. 13 Every vow and every binding oath to afflict her soul, her husband may confirm it, or her husband may make it void.

Matthew Henry's Commentary on Numbers 30:2-13

Commentary on Numbers 30:1-2

(Read Numbers 30:1-2)

No man can be bound by his own promise to do what he is already, by the Divine precept, forbidden to do. In other matters the command is, that he shall not break his words, through he may change his mind.

Commentary on Numbers 30:3-16

(Read Numbers 30:3-16)

Two cases of vows are determined. The case of a daughter in her father's house. When her vow comes to his knowledge, it is in his power either to confirm it or do it away. The law is plain in the case of a wife. If her husband allows her vow, though only by silence, it stands. If he disallows it, her obligation to her husband takes place of it; for to him she ought to be in subjection, as unto the Lord. The Divine law consults the good order of families. It is fit that every man should bear rule in his own house, and have his wife and children in subjection; rather than that this great rule should be broken, or any encouragement be given to inferior relations to break those bonds asunder, God releases the obligation even of a solemn vow. So much does religion secure the welfare of all societies; and in it the families of the earth have a blessing.