Numbers 30:5 - Joseph Benson’s Commentary on the Old and New Testaments

In the day that he heareth Speedily, or without delay, allowing only convenient time for deliberation. And it is hereby intimated, that the day or time he had for disallowing her vow was not to be reckoned from her vowing, but from his knowledge of her vow. The Lord shall forgive Or, will forgive her not performing it. But this should be understood only of vows which could not be performed without invading the father's right; for if one should vow to forbear such or such a sin, and all occasions or means leading to it, and to perform such or such duties, when he had opportunity, no father can discharge him from such vows. If this law does not extend to children's marrying without the parent's consent, so far as to put it in the power of the parent to disannul the marriage, (which some think it does,) yet certainly it proves the sinfulness of such marriages, and obliges those children to repent and humble themselves before God and their parents.