Hadith 17:673
Muhammad ibn Bishr narrated to us, he said: Muhammad ibn ‘Amr narrated to us, from Abu Salamah, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Among the rights of the Muslim upon the Muslim is saying 'Yarhamuk Allah' (may Allah have mercy on you) to the one who sneezes, if he praises Allah."
حدثنا محمد بن بشر قال حدثنا محمد بن عمرو عن أبي سلمة عن أبي هريرة قال قال رسول الله صلى الله عليه وسلم من حق المسلم على المسلم تشميت العاطس إذا حمد الله