If her husband hears about the promise and lets her keep her promise, then she must do exactly what she promised. She must give everything she promised.
“If a person wants to make a special promise to God, or if that person promises to give something special to God, then let him do that thing. But that person must do exactly what he promises!
Hannah’s husband Elkanah said to her, “Do what you think is best. You may stay home until the boy is old enough to eat solid food. May the Lord do what you have said.” So Hannah stayed at home to nurse her son until he was old enough to eat solid food.