What is permissible for a woman to reveal in front of her mahrams?

Question:
Is it considered tabarruj (display of adornment) for a woman to reveal her neck, chest, and arms in her home in the presence of a mahram? And how can a man hold his wife and daughters to the standard of not engaging in tabarruj?

Answer:
The scholars have differed in defining what a mahram is permitted to look at, with several opinions. Among them is what you have heard, that he may look only at what is customarily uncovered, such as the face, earrings, necklace, arm, foot, and lower leg. Others added to this by including the head, upper arms, and the like.
However, the time is dangerous. We are in the end of times, in the alienation of Islam, and many mahrams are open sinners or disbelievers who do not feel secure regarding their mahrams—may Allah protect us from that. She should cover up as much as possible and not take advantage of extra dispensations. Rather, as much as possible, she should reveal only what is customarily uncovered, namely the face, hands, and feet, as this is better for her and safer for her, especially when she is alone with her mahram, such as her open-sin brother, or her open-sin uncle, or her open-sin maternal uncle, for there is great danger in this.
How much have we heard, and how much has reached us, of evils in these matters. Therefore, the best course for a woman in this situation is to be cautious and not say, "This is my mahram" or "This is my maternal uncle." No, especially if she is alone with him and there is no one else present, for the matter is dangerous in this time. The pious is not like the non-pious, and matters concerning women are dangerous even for the most pious, so how much more so for those who are not pious? There is no power and no strength except with Allah.