"O Ka'b bin Murrah! Relate (something) to is from the Messenger of Allah ﷺ, and be cautious. He said: 'I heard the Prophet ﷺ say: "Whoever develops some gray hair in Islam, it shall be a light from him on the Day of Judgement."

حَدِّثْنَا عَنْ رَسُولِ اللَّهِ ﷺ وَاحْذَرْ قَالَ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ مَنْ شَابَ شَيْبَةً فِي الإِسْلاَمِ كَانَتْ لَهُ نُورًا يَوْمَ الْقِيَامَةِ