It was narrated from Safwan bin Umayyah, from his father that he said: I wished that I could see the Messenger of Allah when Revelation was coming down to him. While we were in Al-Jirranah and the Prophet was in a tent, Revelation was coming down to him and 'Umar gestured to me to come. So I put my head into the tent. A man had come to him who had entered Ihram wearing a said: 'O Messenger of Allah, what do you say concerning a man who entered Ihram wearing a Jubbah?'Then (because of this question) the Revelation came. The Prophet started to breath deeply, and when it was over he said: 'Where is the man who asked me just now?' The man was brought to him, and he saidA: 'As for the Jubbah, take it off, and as for the perfume, wash it off, then enter Ihram.'''(Sahih) Chatper 30. The Prohibiton Of Wearing A Shirt In Ihram