The Messenger of Allah ﷺ said, "Whoever turns gray with a single gray hair in the cause of Allah, it will be a light for him on the Day of Resurrection."
حدثنا إسحق بن منصور المروزي أخبرنا حيوة بن شريح الحمصي عن بقية عن بحير بن سعد عن خالد بن معدان عن كثير بن مرة
أن رسول الله ﷺ قال من شاب شيبة في سبيل الله كانت له نورا يوم القيامة
Sahih. Ahmad reported it (4/386) from the hadith of Haywa with the same wording, and Baqiyyah clearly stated that he heard it directly in his version. Nasai also reported it, no. 3144, from the hadith of Amr bin Abasa with the same wording. The hadith has corroborating narrations found in Abu Dawud, no. 3966, and Nasai and others.