Numbers 30:6

And if she had at all an husband, when she vowed, or uttered ought out of her lips, wherewith she bound her soul;

The instruction concerns a woman who already has a husband at the time she makes a vow or speaks words from her lips that bind her soul. It forms part of the directions about vows made to God that cover a wife, a daughter, and others. Within those directions it shows how a woman who is bound by her words is governed while she remains under vow. It also shows how such a vow bears upon husband and wife and on what terms it may be made void.

When the case is a wife cooking swine's flesh for her husband, the instruction supports that she incurs no guilt in doing so at his request.