(2) باب إِذَا صَلَّى خَمْسًا
Narrated' `Abdullah:
Once Allah's Messenger (ﷺ) offered five rak`at in the Zuhr prayer, and somebody asked him whether there was some increase in the prayer. Allah's Messenger (ﷺ) said, "What is that?" He said, "You have offered five rak`at." So Allah's Messenger (ﷺ) performed two prostrations of Sahu after Taslim.
Reference: Sahih al-Bukhari 1226
In-book reference: Book 22, Hadith 3
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 22, Hadith 317