Hadith No: 200

200. Abu Dhar and Abu Darda' Radiyallahu 'anhuma narrate that Rasulullah Sallallahu 'alaihi wasallam said: I will indeed recognize my Ummah among all other Ummahs on the Day of Resurrection. The Sahabah said: O Rasulallah! How would you recognize your people? He said: I will recognize them by their book of deeds in their right hands; I will recognize them from their shining faces due to the prostration marks on their foreheads; and I will recognize them by a light running in front of them. (Musnad Ahmad)

Note: This light will be the light of Iman of every believer, which will be in proportion to the strength of his Iman. (Kashf-ur-Rahman)