Hazrat Abu Huraira narrates that the Messenger of Allah, peace and blessings be upon him, said: A Muslim has a right over another Muslim: when someone sneezes and says "Alhamdulillah," he should respond by saying "Yarhamuk Allah" and pray for him.

Hazrat Abu Huraira narrates that we were sitting with the Noble Prophet (peace and blessings be upon him) when a man sneezed and said, "Alhamdulillah." The Noble Prophet (peace and blessings be upon him) said, "Yarhamukallah." Then another man sneezed, but the Prophet (peace and blessings be upon him) remained silent and did not say anything to him. That man said, "O Messenger of Allah (peace and blessings be upon him)! When he sneezed, you prayed for him by saying 'Yarhamukallah,' but when I sneezed, you did not pray for me!" The Prophet (peace and blessings be upon him) replied, "He said 'Alhamdulillah,' but you remained silent."

Hazrat Ghalib says that Hasan Basri and Hazrat Ibn Sirin, both of these personalities, would not say "Yarhamukallah" as a prayer for the one who sneezed until he said "Alhamdulillah."

Hazrat Ubaidullah narrates that a man sneezed in the presence of Hazrat Qasim, so Hazrat Qasim said to him: Say Alhamdulillah. When he said it, Hazrat Qasim prayed for him by saying Yarhamukallah.

Hazrat Nu’man bin Salim narrates that a man sneezed in the presence of Hazrat Abdullah bin Amr (may Allah be pleased with him), so he supplicated for him by saying“Yarhamukallah”(may Allah have mercy on you). Then the man sneezed again, and he again said“Yarhamukallah.”When the man sneezed a third time, he said:“Surely, you are suffering from a cold.”

Hazrat Harith narrates that Hazrat Ali (may Allah be pleased with him) said: Say "Yarhamukallah" to the one who sneezes when he sneezes three times in front of you; if he sneezes more than that, then it is an illness.

Hazrat Iyas bin Salamah narrates that his father, Hazrat Salamah bin Akwa’, said: A man sneezed in the presence of the Holy Prophet (peace and blessings be upon him), so the Prophet (peace and blessings be upon him) said:“May Allah have mercy on you.”Then the man sneezed a second time, so the Prophet (peace and blessings be upon him) said:“He is suffering from a cold.”

Hazrat Mus'ab bin Abdur Rahman bin Dhuyaib narrates that a man sneezed in the presence of Hazrat Ibn Zubair, so he prayed for him by saying "Yarhamukallah." When he sneezed again, he prayed for him again by saying "Yarhamukallah." When he sneezed a third time, he again prayed for him by saying "Yarhamukallah." Then, when he sneezed a fourth time, Hazrat Abdullah bin Zubair said to him: "Surely, you are suffering from a cold; you should clean your nose."

Imam Sha'bi narrates that Hazrat Amr bin Al-Aas said: When any one of you sneezes three times, then pray for him by saying "Yarhamuk Allah" (may Allah have mercy on you), and if he sneezes more than that, then do not say "Yarhamuk Allah" to him, because this is an illness that is coming out from his head.

Hazrat Muhammad bin Ja'far bin Zubair narrates that a man sneezed in the presence of the Holy Prophet (peace and blessings be upon him), so the Prophet (peace and blessings be upon him) prayed for him by saying "Yarhamuk Allah" (may Allah have mercy on you). Then he sneezed again, and the Prophet (peace and blessings be upon him) prayed for him by saying "Yarhamuk Allah." He sneezed yet again, and the Prophet (peace and blessings be upon him) prayed for him by saying "Yarhamuk Allah." Then, when he sneezed a fourth time, the Holy Prophet (peace and blessings be upon him) said to him: "You are suffering from a cold, go and clean your nose."