Reference: Sharh ‘Umdatil-Fiqh – Tape No.9, Question No.8
Question: Sometimes in Makkah, some men pray wearing the lower part of their ihraam, without the upper part; so should they be advise not to do so?
Response: No, this [act of theirs] is contrary to that which is preferable and safer; [that said], their prayer is still correct in shaa.-Allaah. However, it is preferable and more beautifying that they cover their shoulders, their chests and their backs.
