Ruling on uncovering the face before the husband's brother and his relatives

Question:
My esteemed Shaykh! In the south of the Kingdom, they consider it permissible to uncover the face before the husband's brother and his relatives. What is the response to these people, along with commanding her to do so?

Answer:
This is in the south and in other places. The Messenger of Allah (peace and blessings be upon him) said: It was said: O Messenger of Allah, what do you say about the in-laws? He said: The in-laws are the man's brother and the man's paternal uncle.
If she is lax in uncovering for him, this is one of the means of evil. If she is lax, it indicates the weakness of her faith, and it leads him to covet her. Therefore, it is not permissible for her to uncover, neither for her husband's brother, nor for her husband's paternal uncle, nor for her husband's maternal uncle. Nor is it permissible for her to uncover for her sister's husband, nor for her maternal aunt's husband, nor for her paternal aunt's husband. All of them are strangers to her.
Uncovering is only for her husband's father, her husband's grandfather, and her husband's children. These are the mahram: the husband's children, the children of his sons, and the children of his daughters. They are the mahram. As for the sister's husband, the paternal aunt's husband, and the maternal aunt's husband, these are not mahram. The mahram are her daughter's husband and her mother's husband. These are mahram.