Shaykh Muhammad ibn Saalih al-Uthaymeen rahimahullaah was asked the following question:
Q: What is the ruling on (a woman) wearing tight clothes amongst other women and amongst her relatives that are forbidden for her to marry (her mahrams)?
A: Wearing tight clothes that show off the attractive parts of a woman, and (wearing clothes) that display that which is a cause for trial (fitnah) is forbidden, because the Prophet sallAllaahu `alaihi wa sallam said:
“Two types of the people of Hell I did not see: men with whips like the tails of cows who beat the people with them. [Meaning: oppressively and wrongfully] And women who are dressed but appear to be naked, who are inclined to evil and make their husbands incline towards it. [Saheeh Muslim no. 2128]
So his saying: “Women who are dressed but appear to be naked” has been explained to mean:
1. Those women that wear short clothes that do not cover that which is obligatory to be covered from their awrah (parts that must be covered).
2. And it has (also) been explained to mean: Those women who wear revealing clothes that do not prevent one from seeing that which is behind them from the woman’s skin (i.e. clothes that are see-through).
3. And it has been explained to mean: The women that wear tight clothes that prevent a person seeing (her skin), however they show off the attractive parts of a woman.
Based upon this it is not allowed for a woman to wear these tight clothes except in front of whom she can display her awrah (parts that must be covered) to – and that is her husband – because there is no awrah (parts that must be covered) between a man and his wife, due to His saying:
وَالَّذِينَ هُمْ لِفُرُوجِهِمْ حَافِظُونَ إِلَّا عَلَىٰ أَزْوَاجِهِمْ أَوْ مَا مَلَكَتْ أَيْمَانُهُمْ فَإِنَّهُمْ غَيْرُ مَلُومِينَ
And they who guard their private parts. Except from their wives or those their right hands possess, for indeed, they will not be blamed. [23:5-6]
And Aaishah said: “I used to take baths with the Messenger of Allaah sallAllaahu `alaihi wa sallam. [Meaning: from janaabah (sexual impurity)] From one vessel, that we would alternate taking water from by hand .” [Bukhaaree no. 261 & Muslim no. 321]
As for a woman if she is with her relatives that she is prohibited to marry (mahrams) then it is obligatory for her to cover her `awrah (those parts that must be covered), and tight clothes are not allowed, not in front of her mahrams (the relatives she is prohibited to marry) nor in front of (other) women – if the clothes are very tight and display the attractive parts of a woman.
[Source: The Shaykh’s official website: http://www.ibnothaimeen.com/all/books/article_16956.shtml ]