Numbers 30:7-8, 13

If her husband learns of her vow or pledge and does not object on the day he hears of it, her vows and pledges will stand. But if her husband refuses to accept her vow or impulsive pledge on the day he hears of it, he nullifies her commitments, and the LORD will forgive her.

So her husband may either confirm or nullify any vows or pledges she makes to deny herself.