Sahih Muslim
Sahih Muslim Book 026, Hadith Number 5378.
Hadith Section/Book: Sahih Muslim Sahih Muslim Book 26. On Salutations and Greetings
Chapter : The right of a Muslim upon another Muslim is that his greeting should be responded.
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: Five are the rights of a Muslim over his brother: responding to salutation, saying Yarhamuk Allah when anybody sneezes and says al-Hamdulillah, visiting the sick following the bier.' Abd al-Razzaq said that this hadith has been transmitted as mursal hadith from Zuhri and he then substantiated it on the authority of Ibn Musayyib.
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: Five are the rights of a Muslim over his brother: responding to salutation, saying Yarhamuk Allah when anybody sneezes and says al-Hamdulillah, visiting the sick following the bier.' Abd al-Razzaq said that this hadith has been transmitted as mursal hadith from Zuhri and he then substantiated it on the authority of Ibn Musayyib.