question #1 Sahih al-Bukhari 1225, Book 22, Hadith 2 : What should be done if a mistake is made during the prayer?

Allah’s Messenger (ﷺ) got up after the second rak`a of the Zuhr prayer without sitting in between (the second
and the third rak`at). When he finished the prayer he performed two prostrations (of Sahu) and then
finished the prayer with Taslim.