married a woman whose male cousins used to greet her, but I prevented them from doing this.
I told them that greeting her is Haram (prohibited), but some of them became upset from my words. Even some of my relatives have objected and said that it is not permissible for me to stop them doing this. I explained to them that it is Haram, as they are not her brothers, but her cousins. Please advise me, may Allah reward you with the best.
It is not permissible for a woman to show her beauty, uncover her face, or shake hands with Ajanib (men other than a husband or permanently unmarriageable male relatives). Allah (Exalted be He) says (what means):
And tell the believing women to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts) and not to show off their adornment except only that which is apparent (like both eyes for necessity to see the way, or outer palms of hands or one eye or dress like veil, gloves, head-cover, apron, etc.), and to draw their veils all over Juyûbihinna (i.e. their bodies, faces, necks and bosoms) and not to reveal their adornment except to their husbands, or their fathers, or their husband’s fathers, or their sons, or their husband’s sons, or their brothers or their brother’s sons, or their sister’s sons, or their (Muslim) women (i.e. their sisters in Islâm), or the (female) slaves whom their right hands possess, or old male servants who lack vigour, or small children who have no sense of feminine sex. And let them not stamp their feet so as to reveal what they hide of their adornment. And all of you beg Allâh to forgive you all, O believers, that you may be successful.
(Part No. 17; Page No. 428) The men whom Allah (Glorified be He) mentioned in the Ayah (verse): the woman’s husband, father, father-in-law, brothers, and nephews, etc., these are a woman’s Mahrams (spouse or unmarriageable relatives) and these are the only men it is permissible for her to shake hands with. As for her husband’s brother and uncle, her male cousins, etc., it is not permissible for her to uncover her veil in front of them or to shake hands with them. They can greet her in the presence of her Mahrams, without shaking hands, and with her observing the Hijab and dressing modestly and decently. It is also Haram for them to be in Khulwah (being alone with a member of the opposite sex) with her, as it is authentically reported that the Messenger (peace be upon him) forbade men from visiting and being alone with women, when he said,
“Beware of entering to women.” A man from among the Ansar said, “O Messenger of Allah, what about the in-law?” He said, “The in-law is death.”
The in-law refers to the husband’s relatives, such as his brother, paternal and maternal uncles, etc. As for your relatives being upset, do not pay any attention to it; you have to invite them to the Truth and explain it to them with evidence, hoping that Allah will guide them. May Allah grant us success. May peace and blessings be upon our Prophet, his family, and Companions.