It wasnarrated from Ibn 'Umar that the Messenger of Allah (ﷺ)forgotand said the Taslim after two Rak'ah. A man who was calledDhul-Yadain said to him:
'O Messenger of Allah, has the prayer beenshortened or did you forget?' He said: 'It has not been shortenedandI did not forget.' He said: 'But you prayed two Rak'ah.' Hesaid: 'Is whatDhul-Yadain says true?' They said: 'Yes.' Sohe went forward andperformed two Rak'ah and said the Salam, thenhe prostrated twice forprostrations of forgetfulness. (ID)
English reference (ID): Vol. 1, Book 5, Hadith 1213 (ID)
Arabic reference (ID): Book 5, Hadith 1270 (ID)