1. If a wife makes a vow to fast the first nine days of Dhul-Hijjah on a permanent basis, it is a vow to do an act of obedience and she is obliged to fulfill it. 2. The husband does not have the right to prevent her from doing that, because her husband may only prevent her from observing voluntary fasts. Please see the details below.

The Quran is the Word of Allah, and the Quran is one of the attributes of Allah. So if a person says “By the Quran” or “By the life of the Quran”, there is nothing wrong with that.