It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) (the narrator thinks it is narrated from him) that the Prophet (peace and blessings be upon him) saw Jibril (peace be upon him) in his true form only twice. He said: As for the first time, he (peace and blessings be upon him) asked him to show himself to him in his true form, and he showed him; so he came to him (peace and blessings be upon him) filling the horizon. As for the second time, he was with him when he (peace and blessings be upon him) ascended, (which is mentioned) in the saying of Allah Almighty: "Then he drew near and came down, and was at a distance of two bow-lengths or even nearer. Then He revealed to His servant what He revealed" [Surah al-Najm: 9]. Then when Jibril (peace be upon him) sensed (the nearness of) his Lord, the Mighty and Majestic, he returned to his true form. This is what is meant by the saying of Allah Almighty: "And he certainly saw him (Jibril) another time (in his true form), at the Lote Tree of the Utmost Boundary" [Surah al-Najm: 13] "near which is the Garden of Refuge", up to the saying of Allah Almighty: "He certainly saw (one) of the greatest signs of his Lord" [Surah al-Najm: 18]. He said: "That was (the sign of) the (true) form of Jibril (peace be upon him)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10501