Qur'an, An-Najm, Surah 53:1-12
By the setting star, your comrade [Muhammad] has not gone astray, neither is he deceived, nor following his own desire. This Qur'an is a divine inspiration revealed to him by the mighty one [Gabriel]. Endowed with incredible power he made himself manifest on the uppermost horizon of the sky. Then drawing nearer he came downward until he was only two bow-lengths away from him. Thus Allah made His revelations manifest to the chosen servant. His own heart did not belie the vision. Then how can you dispute with him?