Clothes Made from Thin Material
Question :
Thin clothing has increased among the Muslim popula- tion, especially in the summer time. Many of the people wear such clothing during prayer, while wearing under- clothing that extends to the middle or third of their thighs. Some of them wear underclothing below their navel that is visible beneath their Thawh.
As you know, noble Shaikh, covering the 'Awrah (body parts that must be covered) is a requisite for the correctness of prayer, and this is an important issue because prayer is a pillar of the religion. Please advise the Imams of the Masjids and those who give Khutbahs to speak to the people about this practice, which has become prevalent among most of those who attend the prayer.
Answer:
We thank you and appreciate your concerns about the prayer, for indeed it is the most important physical act of worship. We will try, as you asked, to make people aware of this issue as much as possible. However, we do believe that clothes made from thin material are acceptable and that they do perform the job of covering what is required to be covered, if Allah wills, with the condition that the material doesn't reveal the skin. underneath it, its whiteness or darkness for example. But still, being cautious is always better. And Allah Almighty knows best.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 7 Page 379