Sunan At-Tirmidhi

Narrated Amr bin 'Abasah: 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. [Abu 'Eisa said:] This Hadith is Hasan Sahih Gharib. As for Haiwah bin Shuraih, (the remainder of his name is) Ibn Yazid Al-Himsi