[Machine] The Messenger of Allah, peace be upon him, forbade wearing two garments at once, so that there is nothing between one's private parts and the sky. He also forbade wearing the saummah, which was a specific type of garment worn by Jewish people.  

نَهَى رَسُولُ اللَّهِ ﷺ عَنْ لِبْسَتَيْنِ أَنْ يَحْتَبِيَ أَحَدُكُمْ فِي الثَّوْبِ الْوَاحِدِ لَيْسَ بَيْنَ فَرْجِهِ وَبَيْنَ السَّمَاءِ شَيْءٌ وَعَنِ الصَّمَّاءِ اشْتِمَالِ الْيَهُودِ