It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) said: When one of you sneezes, he should say "Alhamdulillah." His Muslim brother who hears him say "Alhamdulillah" should say to him "Yarhamukallah." Then the one who sneezed should say "Yahdikumullah wa yuslihu balakum."