Al-Adab Al-Mufrad #627

Safwan ibn 'Abdullah ibn Safwan, who was married to the daughter of Abu'd-Darda', said, "I visited them in Syria and found Umm ad-Darda' in the house, but not Abu'd-Darda'. She asked, 'Are you intending to go on hajj this year?' 'Yes,' I replied. She said, 'Make supplication to Allah and ask for good for us. The Prophet, may Allah bless him and grant him peace, said, "The supplication of a Muslim man for his absent brother is answered. At his head there is a guardian angel. Whenever he asks Allah to give his brother good, the angel says, 'Amen, and may you have the same.'"' I met Abu'd-Darda' in the market and he said something similar which was related from the Prophet, may Allah bless him and grant him peace."