(22) باب مَا يَفْعَلُ مَنْ سَلَّمَ مِنْ رَكْعَتَيْنِ نَاسِيًا وَتَكَلَّمَ
It was narrated that Abu Hurairah said:
"The Messenger of Allah (ﷺ) forgot and said the taslim after two rak'ahs. Dhul-Shimalain said to him: 'Has the prayer been shortened or did you forget, O Messenger of Allah (ﷺ)?' The Messenger of Allah (ﷺ) said: 'Is Dhul-Yadain speaking the truth?' They said: "Yes." So the Messenger of Allah (ﷺ) stood up and completed the prayer."
Reference: Sunan an-Nasa'i 1229
In-book reference: Book 13, Hadith 51
English translation: Vol. 2, Book 13, Hadith 1230