It was narrated from Ibn ‘Umar that the Messenger of Allah (ﷺ) forgot and said the Taslim after two Rak’ah. A man who was called Dhul-Yadain said to him:
‘O Messenger of Allah, has the prayer been shortened or did you forget?’ He said: ‘It has not been shortened and I did not forget.’ He said: ‘But you prayed two Rak’ah.’ He said: ‘Is what Dhul-Yadain says true?’ They said: ‘Yes.’ So he went forward and performed two Rak’ah and said the Salam, then he prostrated twice for prostrations of forgetfulness.
حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، وَأَبُو كُرَيْبٍ وَأَحْمَدُ بْنُ سِنَانٍ قَالُوا حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ سَهَا فَسَلَّمَ فِي الرَّكْعَتَيْنِ ‏.‏ فَقَالَ لَهُ رَجُلٌ يُقَالُ لَهُ ذُو الْيَدَيْنِ يَا رَسُولَ اللَّهِ أَقَصُرَتِ الصَّلاَةُ أَمْ نَسِيتَ قَالَ ‏"‏ مَا قَصُرَتْ وَمَا نَسِيتُ ‏"‏ ‏.‏ قَالَ إِنَّكَ صَلَّيْتَ رَكْعَتَيْنِ ‏.‏ قَالَ ‏"‏ أَكَمَا يَقُولُ ذُو الْيَدَيْنِ ‏"‏ ‏.‏ قَالُوا نَعَمْ ‏.‏ فَتَقَدَّمَ فَصَلَّى رَكْعَتَيْنِ ثُمَّ سَلَّمَ ثُمَّ سَجَدَ سَجْدَتَىِ السَّهْوِ ‏.‏
GradeSahih (Darussalam)
English reference : Vol. 1, Book 5, Hadith 1213
Arabic reference : Book 5, Hadith 1270