I heard from somebody that not wearing under garments is sunnah. So I would like to know about wearing and not wearing of under garments in case of both Muslim men and women. Please explain in the light of Quran and Hadith if any.
بسم الله الرحمن الرحيم
It is the common ruling of Shariah regarding the dress that they cover those body parts which are necessary to be covered. Also they do not resemble the dresses of the non-Muslims. If underwear is worn underneath the garments by which the structure and size of coverable body parts are not exposed then according to the Shariah there is no harm in wearing underwear for men and women, rather it will be lawful, it cannot be termed against the Sunnah. Yes, only wearing the underwear which exposes the body structure is not right.
Allah knows Best!
Darul Uloom Deoband