Sahih Bukhari Volume 008, Book 078, Hadith Number 663.

Narated By 'Abdullah bin Buhaina : Once Allah's Apostle led us in prayer, and after finishing the first two Rakat, got up (instead of sitting for At-Tahiyyat) and then carried on with the prayer. When he had finished his prayer, the people were waiting for him to say Taslim, but before saying Tasiim, he said Takbir and prostrated; then he raised his head, and saying Takbir, he prostrated (SAHU) and then raised his head and finished his prayer with Taslim.