Hadith 17:672
Qasim ibn Malik al-Muzani narrated to us, from Asim ibn Kulayb, from Abu Burdah, who said: I entered upon Abu Musa while he was in the house of the daughter of al-Fadl. I sneezed, and he did not say "Yarhamuk Allah" (may Allah have mercy on you) to me. Then she sneezed, and he said "Yarhamuk Allah" to her. I returned to my mother and informed her. When he came to her, she said: "My son sneezed in your presence and you did not say 'Yarhamuk Allah' to him, but she sneezed and you said 'Yarhamuk Allah' to her?" He said: "Your son sneezed and did not praise Allah, so I did not say 'Yarhamuk Allah' to him. She sneezed and praised Allah, so I said 'Yarhamuk Allah' to her. I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'If one of you sneezes and praises Allah, then say "Yarhamuk Allah" to him; but if he does not praise Allah, then do not say "Yarhamuk Allah" to him.'"
حدثنا قاسم بن مالك المزني عن عاصم بن كليب عن أبي بردة قال دخلت على أبي موسى وهو في بيت بنت الفضل فعطست فلم يشمتني وعطست فشمتها فرجعت إلى أمي فأخبرتها فلما جاءها قالت عطس عندك ابني فلم تشمته وعطست فشمتها قال إن ابنك عطس ولم يحمد الله فلم أشمته وعطست وحمدت الله فشمتها وسمعت رسول الله صلى الله عليه وسلم يقول إذا عطس أحدكم فحمد الله فشمتوه وإذا لم يحمد الله فلا تشمتوه