Iyas ibn Salama related that his father said, "A man sneezed inthe presence of the Prophet, may Allah bless him and grant him peace, andthe Prophet said, 'May Allah have mercy on you.' Then the man sneezed againand the Prophet, may Allah bless him and grant him peace, said, 'This manhas a cold.'"
English reference: Book 40, Hadith 935
Arabic reference: Book 1, Hadith 935