Mu'awiyah bin al-Hakam al-Sulami (may Allah be pleased with him) narrates: Once I was praying (in congregation) with the Messenger of Allah (peace and blessings be upon him) when a man sneezed, and I said: 'Yarhamuk Allah' (May Allah have mercy on you). The people began to stare at me. I said: Woe is me, may my mother lose me! Why are you looking at me? Then they began striking their thighs with their hands. When I saw that they were silencing me, I fell silent. When the Messenger of Allah (peace and blessings be upon him) finished the prayer, he called me, may my father and mother be ransomed for him (peace and blessings be upon him). I have never seen, before him or after him, a teacher like the Messenger of Allah (peace and blessings be upon him), better in teaching than him (peace and blessings be upon him). By Allah, he (peace and blessings be upon him) neither struck me, nor scolded me, nor reviled me; he only said: "This is the prayer; talking and the like is not permissible in it. It consists of tasbih, takbir and the recitation of the Qur'an."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3349