Is the husband who believes the niqab is obligatory sinful if his wife does not believe so and refuses to wear it and the mulhafa, knowing that she wears loose clothing, and what is your advice for convincing her or the evidence that proves its obligation?

A wife is obliged to obey her husband in matters of permissible disagreement, as long as this obedience does not lead her to believe something is forbidden or to abandon an obligation. The husband should strive to encourage his wife to wear the niqab and persuade her to do so within his capacity. We advise the wife to cover her face, as it is further removed from fitnah (temptation/strife), resolves scholarly differences, and entails obedience to her husband.