Ibn Al-Mundhir recorded that `Ikrimah commented on this Ayah,
[وَلاَ يُبْدِينَ زِينَتَهُنَّ إِلاَّ لِبُعُولَتِهِنَّ أَوْ ءَابَآئِهِنَّ أَوْ ءَابَآءِ بُعُولَتِهِنَّ]
(and not to reveal their adornment except to their husbands, or their fathers, or their husband’s fathers…), “The paternal uncle and maternal uncle are not mentioned here, because they may describe a woman to their sons, so a woman should not remove her Khimar in front of her paternal or maternal uncle.”With regard to the husband, all of this is for his sake, so she should try her best when adorning herself for him, unlike the way she should appear in front of others.
(or their women,) this means that she may also wear her adornment in front of other Muslim women, but not in front of the women of Ahl Adh-Dhimmah (Jewish and Christian women), lest they describe her to their husbands. This is prohibited for all women, but more so in the case of the women of Ahl Adh-Dhimmah, because there is nothing to prevent them from doing that, but Muslim women know that it is unlawful and so, would be deterred from doing it. The Messenger of Allah said:
«لَا تُبَاشِرِ الْمَرْأَةُ الْمَرْأَةَ فَتَنْعَتَهَا لِزَوْجِهَا كَأَنَّهُ يَنْظُرُ إِلَيْهَا»
(No woman should describe another woman to her husband so that it is as if he is looking at her.) It was recorded in the Two Sahihs from Ibn Mas`ud.
Tafsir Ibn Kathir, Surah An-Nur