Messenger of Allah ﷺ once led us in a prayer and offered two rakʿat and got up (for the third rakʿa) without sitting (after the second rakʿa). 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.  

أَنَّهُ قَالَ صَلَّى لَنَا رَسُولُ اللَّهِ ﷺ رَكْعَتَيْنِ مِنْ بَعْضِ الصَّلَوَاتِ ثُمَّ قَامَ فَلَمْ يَجْلِسْ فَقَامَ النَّاسُ مَعَهُ فَلَمَّا قَضَى صَلاَتَهُ وَنَظَرْنَا تَسْلِيمَهُ كَبَّرَ قَبْلَ التَّسْلِيمِ فَسَجَدَ سَجْدَتَيْنِ وَهُوَ جَالِسٌ ثُمَّ سَلَّمَ  

Messenger of Allah ﷺ got up after the second rakʿa of the Zuhr prayer without sitting in between (the second and the third rakʿat). When he finished the prayer he performed two prostrations (of Sahu) and then finished the prayer with Taslim.  

أَنَّهُ قَالَ إِنَّ رَسُولَ اللَّهِ ﷺ قَامَ مِنِ اثْنَتَيْنِ مِنَ الظُّهْرِ لَمْ يَجْلِسْ بَيْنَهُمَا فَلَمَّا قَضَى صَلاَتَهُ سَجَدَ سَجْدَتَيْنِ ثُمَّ سَلَّمَ بَعْدَ ذَلِكَ