Sahih Bukhari
Actions while Praying
Volume: 002 / Book Number: 022 / Hadith Number: 317
Narrated' Abdullah:
Once Allah's Apostle offered five Rakat in the Zuhr prayer, and somebody asked him whether there was some increase in the prayer. Allah's Apostle said, "What is that?" He said, "You have offered five Rakat." So Allah's Apostle performed two prostrations of Sahu after Taslim.