" And certainly he saw him in another descent" (al-Quran, Iiii. 13) imply that he saw Gabriel.
Sahih Muslim Book 1, Hadith 340
← Previous Hadith " Certainly he saw of the greatest signs of Allah" (al-Quran, liii. 18) imply that he saw Gabriel in his (original) form and he had six hundred wings.

Sahih Muslim Book 1, Hadith 339 Next Hadith → It is narrated on the authority of Ibn 'Abbas that he (the Holy Prophet) saw (Allah) with, his heart.

Sahih Muslim Book 1, Hadith 341