Concise Quran Commentary
Your companion had seen Gabriel in the form that he was created in the clear horizon of the sky.
Tafsir for this Ayah
Surah 81 : Ayah 23
Surah 81 : Ayah 23
وَلَقَدْ رَءَاهُ بِٱلْأُفُقِ ٱلْمُبِينِ
He indeed saw him [i.e., Gabriel] on the clear horizon[7].