Sahih Muslim Book - 1, Hadith - 442

و حَدَّثَنَا ابْنُ نُمَيْرٍ حَدَّثَنَا أَبُو أُسَامَةَ حَدَّثَنَا زَكَرِيَّاءُ عَنْ ابْنِ أَشْوَعَ عَنْ عَامِرٍ عَنْ مَسْرُوقٍ قَالَ قُلْتُ لِعَائِشَةَ فَأَيْنَ قَوْله { ثُمَّ دَنَا فَتَدَلَّى فَكَانَ قَابَ قَوْسَيْنِ أَوْ أَدْنَى فَأَوْحَى إِلَى عَبْدِهِ مَا أَوْحَى } قَالَتْ إِنَّمَا ذَاكَ جِبْرِيلُ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يَأْتِيهِ فِي صُورَةِ الرِّجَالِ وَإِنَّهُ أَتَاهُ فِي هَذِهِ الْمَرَّةِ فِي صُورَتِهِ الَّتِي هِيَ صُورَتُهُ فَسَدَّ أُفُقَ السَّمَاءِ.

It was narrated that Masruq said: "I said to 'Aishah: 'What is the meaning of the saying of Allah, the Most High: Then he approached and came closer. And was at a distance of two bows' length or (even) nearer. So (Allah) revealed to His slave whatever He revealed.?' She said: 'That was Jibril. He used to come to him in the form of a man, but on this occasion he came in the form which was his true form, and he filled the horizon of the sky."'