(7) بَابُ إِذَا قَالَ أَحَدُكُمْ آمِينَ. وَالْمَلاَئِكَةُ فِي السَّمَاءِ، فَوَافَقَتْ إِحْدَاهُمَا الأُخْرَى، غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ
Narrated Aisha:
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.
Reference: Sahih al-Bukhari 3234
In-book reference: Book 59, Hadith 45
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 54, Hadith 457