"al-Shuʿab" (7/25/9330), and Aḥmad (4/412) - and the context is his -; they said: Qāsim ibn Mālik Abū Jaʿfar narrated to us: ʿĀṣim ibn Kulayb narrated to us from Abū Burdah who said: I entered upon Abū Mūsá in the house of the daughter of Umm al-Faḍl, I sneezed and he did not say "may Allāh have mercy on you" to me, but when she sneezed, he said it to her. So I returned to my mother and informed her. When she came to him, she said: My son sneezed in your presence and you did not say "may Allāh have mercy on you" to him, but when she sneezed, you did? He replied: Your son sneezed and did not praise Allāh, so I did not say it to him, but she sneezed and praised Allāh, so I said it to her. And I heard the Messenger of Allāh (ṣallá Allāhu ʿalayhi wa-sallam) say... and he mentioned it. She said: You did well, you did well... From this perspective, it was recorded by Muslim (8/225), al-Bukhārī in "al-Adab al-Mufrad" (941), al-Ṭabarānī in "al-Duʿāʾ" (3/1694/1997), and al-Ḥākim (4/265) who said: "Its chain of transmission is authentic, and they did not record it!" and al-Dhahabī agreed! This is what they said, but they erred in their correction regarding Muslim! (Benefit): al-Nawawī said in "Sharḥ Muslim": "This daughter is Umm Kulthūm, the daughter of al-Faḍl ibn al-ʿAbbās, the wife of Abū Mūsá al-Ashʿarī. He married her after al-Ḥasan ibn ʿAlī separated from her, and she bore children for Abū Mūsá, and he died leaving her; then ʿImrān ibn Ṭalḥah married her and separated from her, and she died in Kūfah and was buried outside it." (Note): The word "daughter" was omitted from "al-Adab al-Mufrad" in the edition by Muḥibb al-Dīn al-Khaṭīb, and the edition by al-Jaylānī (4/393) said: "in the house of Umm al-Faḍl ibn al-ʿAbbās." I suspect this is from some of the copyists. Know that it is well-known among the scholars that saying "may Allāh have mercy on you" is a communal obligation, so if some fulfill it, it is no longer required of the others. However, it has been authentically reported from Abū Hurayrah in a raised ḥadīth with the wording: