Is the husband sinful if he allows his wife to wear makeup under her niqab and uncover her face adorned with cosmetics in front of male and female relatives, despite his repeated advice to her?

It is not permissible for a woman to uncover her face in front of non-mahrams unless there is a need, and uncovering it while wearing makeup is even more strictly prohibited. The husband must prevent his wife from doing so, and he is accountable before Allah for his household. Furthermore, the wife is commanded to obey her husband in what he enjoins upon her of duties or prohibits her from unlawful acts. If she insists on uncovering her face, she should not be allowed to go out. Her disobedience can be addressed by admonition, then by desertion, then by light, non-injurious physical discipline, and then by seeking the intervention of two arbitrators.