All perfect praise be to Allah the Lord of the Worlds. May Allah`s peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

In principle, all clothes are permissible unless there is a clear text that says they are impermissible (Haram). Scholars stated that it is permissible to wear the pants that are thick, non-tight, non-outlining, and non-defining of the Awrah (What should be covered of the body). Whereas, it is reprehensible to wear pants that outline and define the Awrah. Jarir Bin Abdullah said: "The man who wears clothes that outline and define his Awrah is as good as naked." {Related by Tabarani in Al-Mo`jam Al-Kabeer, vol.2/pp.292}.

As for young Muslim women, it is customary that they wear pants under their Jilbab.

We (Iftaa` Department) advise young Muslim women to wear the Islamic dress that isn`t tight and doesn`t outline or define the body. This is attested to in the Hadith narrated by Usamah Ibn Zaid (May Allah be pleased with him) who said: "The Prophet (PBUH) gifted me thin garment made in Egypt, so I gave it to my wife. One day, he asked me: "Why aren`t you wearing that Egyptian garment?" I replied, " O! Messenger of Allah, I have given it to my wife." He said: "Ask her to wear an undergarment because I fear that it could define and outline her body." {Related by Ahmad in his Musnad,vol.36/pp.120}. And Allah the Almighty Knows Best.