Musa عليه السلام Fire- Who Was In It?
I don’t know and neither am I inclined to know. At another place, Quran ( 28:30 ), it is mentioned that voice came from the nearby tree. This is one of the way (among three) that God used to communicate with prophets, the reality of these events can’t be known by us. (Please see the caption “The Essence of Prophethood” for further details: Discussion 15736 ) The Quran has specified that nature of wahi is beyond the comprehension of man: وَيَسْأَلُوْنَكَ عَنِ الرُّوْحِ قُلِ الرُّوْحُ مِنْ أَمْرِ رَبِّيْ وَمَآ أُوتِيْتُمْ مِّنِ الْعِلْمِ إِلاَّ قَلِيْلاً (85:17) And they ask you about al-ruh [– ie. the wahi –]. Tell them: “This al-ruh is from among my Lord’s command. Little indeed is the knowledge given to you .” ( 17:85 )
It is wahi and we have no way of knowing how that works.