From Sahih Bukhari (Hadith 1224):
Narrated `Abdullah bin Buhaina:Allah's Messenger (ﷺ) once led us in a prayer and offered two rak`at and got up (for the third rak`a) without sitting (after the second rak`a). The people also got up with him, and when he was about to finish his prayer, we waited for him to finish the prayer with Taslim but he said Takbir before Taslim and performed two prostrations while sitting and then finished the prayer with Taslim
Reference: Bukhari 1224