Who named the prayers Fajr, Dhuhr, Asr, Maghrib, and Isha? And was it the Prophet, peace and blessings be upon him, who named them, or the Companions and the Successors? And do these names have a significance?

Naming the prayers with their known names today is established and well-known in Islamic sources, and it has reached the level of tawatur (successive transmission). Some of these names have appeared in the Holy Quran, as in His saying, the Almighty: "Establish prayer at the decline of the sun [from its meridian] until the darkness of the night and [also] the Quran of dawn." And in another verse, there is an explicit mention of the names of other prayers, as in His saying, the Mighty and Majestic: "Before the prayer of dawn and when you put aside your clothing at noon and after the prayer of 'Isha." The beginning of naming the prayers with these names was at the beginning of Islam, when Gabriel, peace be upon him, descended to teach the Prophet, peace and blessings be upon him, those timings, so he named them with those names, and they spread and became established as such to this day. Gabriel, peace be upon him, led the Prophet, peace and blessings be upon him, in prayer twice at the House (Kaaba), and he prayed with him the prayers with their known names. So the hadiths in which the names of the prayers are mentioned are very numerous, and they are tawqifi names (divinely appointed) that Gabriel taught to the Prophet, peace and blessings be upon him, when prayer was enjoined upon him.