Sahih al-Bukhari, Hadith 1226 ⓘ

Narrated' `Abdullah: Once Allah's Messenger offered five rak`at in the Zuhr prayer, and somebody asked him whether there was some increase in the prayer. Allah's Messenger said, "What is that?" He said, "You have offered five rak`at." So Allah's Messenger performed two prostrations of Sahu after Taslim.

حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى الظُّهْرَ خَمْسًا فَقِيلَ لَهُ أَزِيدَ فِي الصَّلاَةِ فَقَالَ ‏ "‏ وَمَا ذَاكَ ‏" ‏‏.‏ قَالَ صَلَّيْتَ خَمْسًا‏.‏ فَسَجَدَ سَجْدَتَيْنِ بَعْدَ مَا سَلَّمَ‏.‏