"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  

That the Messenger of Allah ﷺ said: "Whoever develops some gray hair in the cause of Allah, it shall be a light for him in the Day of Judgement.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ مَنْ شَابَ شَيْبَةً فِي سَبِيلِ اللَّهِ كَانَتْ لَهُ نُورًا يَوْمَ الْقِيَامَةِ