What are the two times the Prophet (peace and blessings be upon him) saw Gabriel (peace be upon him) as mentioned in Surat An-Najm, and was the first time at the highest horizon when the revelation descended, and the second time at the Lote Tree of the Utmost Boundary, and how do we reconcile this with the description of seeing the Trustworthy Spirit in Surat Al-Muddathir?

The Prophet, peace and blessings be upon him, saw Jibril, peace be upon him, in his true form, as Allah created him, only twice:

The first time was at the beginning of the revelation on Earth, after which Surah Al-Muddaththir was revealed. This is mentioned in the Almighty's saying: "And he had already seen him in the clear horizon." (At-Takwir/23).

The second time was in the heavens on the night of Al-Isra' wal-Mi'raj, at the Lote Tree of the Utmost Boundary. This is mentioned in the Almighty's saying: "And he had already seen him yet another time, at the Lote Tree of the Utmost Boundary." (An-Najm/13-14).

The Prophet, peace and blessings be upon him, affirmed that he did not see him in the form in which he was created except on these two occasions.