The Messenger of Allah ﷺ said, "Whoever grows a single grey hair in the path of Allah, it will be a light for him on the Day of Resurrection."
أن رسول الله ﷺ قال: من شاب شيبة في سبيل الله كانت له نورا يوم القيامة.
Tirmidhi (1635) and Ahmad (19440) both narrated it through Haywa bin Shurayh Himsi, from Baqiyya, from Buhayr bin Saad, from Khalid bin Madan, from Kathir bin Mura, from Amr bin Abasa, and he related it. Tirmidhi said, "This is a hadith hasan sahih ghareeb, and Haywa bin Shurayh is Ibn Yazid Himsi."I say, its chain is hasan because of Baqiyya, who is Ibn Walid, a mudallis, but his use of "an" (indirect transmission) from Buhayr bin Saad is accepted. Ibn Hibban also narrated it in his Sahih (2984) through another route from Amr bin Abasa, who is Abu Najeeh Sulami, and it has other routes besides, though what I have mentioned is the soundest of them.