Q 1: Allah (Exalted be He) says:
Tell the believing men to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts). That is purer for them. Verily, Allâh is All-Aware of what they do.
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. 295) In this Ayah (Qur’anic verse), there is no mention of paternal or maternal uncles, although they are also Mahrams (unmarriageable relatives), is it sinful for a woman to show her adornment in front of them?
A:
It is not sinful for a man to look at his maternal niece or her adornment, because she is one of his Mahrams, as Allah says (what means):
Forbidden to you (for marriage) are: your mothers, your daughters
to:
...your brother’s daughters, your sister’s daughters
Also, it can be concluded that permission is given to a niece to show her adornment in front of her paternal or maternal uncles from the general meaning of the permission given to an aunt to show her adornment in front of her paternal or maternal nephews. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.