Numbers 30:11
And her husband heard it, and held his peace at her, and disallowed her not: then all her vows shall stand, and every bond wherewith she bound her soul shall stand. And her husband heard it, and held his peace at her, and disallowed her not: then all her vows shall stand, and every bond wherewith she bound her soul shall stand.
When a husband hears his wife's vow and holds his peace at her without disallowing it, then all her vows shall stand and every bond by which she has bound her soul shall stand in full force. Silence without forbidding leaves the vow and every binding obligation she has taken upon herself remaining and obligatory. A vow becomes void only under the specified circumstances set out in Numbers 30 involving a wife and her husband or a daughter and her father.
The chapter calls for examining whether vows are being faithfully kept. In the case of a wife cooking swine's flesh for her husband, the rule means she is not held guilty for doing so merely because he wants it.