Question: What is the ruling on wearing trousers for women and men?
Answer: I do not see any objection if it is in a form that does not describe the Awrah (parts that have to be covered and hidden in the Islamic Shariah), but rather covers them and does not involve imitation (of the opposite gender). Pants specifically designed for men should not be worn by women, and those designed for women should not be worn by men. If the style is specific to non-Muslims, it should not be worn by Muslims either.
In summary – both men and women should ensure that their clothing does not resemble that of the opposite gender, whether in pants or other garments. Additionally, it should not resemble clothing specific to non-Muslims. However, shared styles that are not exclusive to non-Muslims are permissible. Similarly, items that are not exclusive to either gender, such as silver rings, are permissible as they are not specific to anyone (male or female).
Presenter: The reality of pants, esteemed Shaikh, is that they outline the body parts?
Shaikh: If they outline the private parts and body features, causing temptation, women should avoid wearing them except in the presence of their husbands.
Presenter: Thank you. What about in front of her close male relatives?
Answer: It is also advisable to avoid it.
Presenter: To avoid it (i.e wearing pants).
Shaikh: To prevent Fithnah (referring to exposing of the Awrah or shape of the Awrah). Yes.
[Answered by Shaikh Abdul Azeez bin Abdullah bin Baaz (Rahimahullah) on Fatawa Noor Ala-Ad-Darb.]
Saheehus-Seerah 