The Messenger of Allah ﷺ led us in prayer praying two rak'ahs. When he stood up and did not sit (at the end of two rak'ahs) the people stood up along with him. When he finished the prayer and we expect him to give the salutation, he said: "Allah is most great." While sitting and made two prostrations before giving the salutation. Then he gave it. (Using translation from Abū Dāʾūd 1034)  

«صَلَّى بِنَا رَسُولُ اللهِ ﷺ رَكْعَتَيْنِ ثُمَّ قَامَ فَلَمْ يَجْلِسْ فَقَامَ النَّاسُ مَعَهُ فَلَمَّا قَضَى صَلَاتَهُ وَنَظَرْنَا تَسْلِيمَهُ كَبَّرَ فَسَجَدَ سَجْدَتَيْنِ وَهُوَ جَالِسٌ قَبْلَ التَّسْلِيمِ ثُمَّ سَلَّمَ»  

The Messenger of Allah ﷺ stood up during the prayer when he should have sat, so he prostrated twice while sitting, before the taslim. (Using translation from Nasāʾī 1223)  

عَنْ رَسُولِ اللهِ ﷺ أَنَّهُ «قَامَ فِي الصَّلَاةِ وَعَلَيْهِ جُلُوسٌ فَسَجَدَ سَجْدَتَيْنِ وَهُوَ جَالِسٌ قَبْلَ التَّسْلِيمِ»