Sahih Muslim Book - 5, Hadith - 1269

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ عَنْ عَبْدِ الرَّحْمَنِ الأَعْرَجِ عَنْ عَبْدِ اللَّهِ ابْنِ بُحَيْنَةَ قَالَ صَلَّى لَنَا رَسُولُ اللَّهِ -صلى الله عليه وسلم- رَكْعَتَيْنِ مِنْ بَعْضِ الصَّلَوَاتِ ثُمَّ قَامَ فَلَمْ يَجْلِسْ فَقَامَ النَّاسُ مَعَهُ فَلَمَّا قَضَى صَلاَتَهُ وَنَظَرْنَا تَسْلِيمَهُ كَبَّرَ فَسَجَدَ سَجْدَتَيْنِ وَهُوَ جَالِسٌ قَبْلَ التَّسْلِيمِ ثُمَّ سَلَّمَ.

It was narrated that 'Abdullah bin Buhainah, said: "The Messenger of Allah (s.a.w) led us in praying two Rak'ah of one of the prayers, then he stood up without sitting, and the people stood up with him. When he had finished his prayer and we were waiting for him to say the Taslim, he said the Takbir, then he prostrated twice while he was sitting, before saying the Taslim, then he said the Taslim."