*Important Clarification*
Shaykh Saalih al-Fawzaan was asked in this video clip about the permissibility of a Muslim woman uncovering in front of her non-Muslim mother and sisters. He said that it is permissible for her to do so and the proof is Allaah's statement (in Soorah an-Noor 24:31) "... and their women". He said that this includes both Muslim and non-Muslim women and the position that it refers only to Muslim women is baseless. And Allaah knows best.