Hazrat Anas bin Malik (may Allah be pleased with him) narrated that two companions sneezed in the presence of the Prophet Muhammad (peace and blessings be upon him). The Prophet (peace be upon him) replied to one by saying "Yarhamuk Allah" (May Allah have mercy on you), but did not reply to the other. When the reason for this was asked, the Prophet (peace be upon him) said that the first had said "Alhamdulillah" (All praise is due to Allah), so he replied to him, but the other had not said "Alhamdulillah".

Hazrat Abu Huraira (may Allah be pleased with him) narrated that the Noble Prophet (peace and blessings be upon him) said: Yawning is from Satan. So when any one of you feels like yawning, he should try to restrain it as much as possible.