Sahih al-Bukhari 3234
Sahih al-Bukhari · Book 59: Beginning of Creation · If anyone says Amin [during the Salat (prayer) at the end of the recitation of Surat Al-Fatiha]
Narrated Aisha:
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ إِسْمَاعِيلَ ، حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ الأَنْصَارِيُّ ، عَنِ ابْنِ عَوْنٍ ، أَنْبَأَنَا الْقَاسِمُ ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ مَنْ زَعَمَ أَنَّ مُحَمَّدًا رَأَى رَبَّهُ فَقَدْ أَعْظَمَ، وَلَكِنْ قَدْ رَأَى جِبْرِيلَ فِي صُورَتِهِ، وَخَلْقُهُ سَادٌّ مَا بَيْنَ الأُفُقِ.
Whoever claimed that (the Prophet) Muhammad saw his Lord, is committing a great fault, for he only saw Gabriel in his genuine shape in which he was created covering the whole horizon.