Sahih Bukhari Volume 8, Book 73, Hadith Number 244.

Narated By Anas : Two men sneezed before the Prophet and he said Tashmit to one of them, while he did not say Tashmit to the other. So that man said, “O Allah’s Apostle! You said Tashmit to that fellow but you did not say Tashmit to me. “The Prophet said, “That man praised Allah, but you did not praise Allah.”