Sahih al-Bukhari, Volume 9, Book 91, Hadith 355 (USC-MSA) ⓘ

Narrated `Abdullah: The Prophet led us in Zuhr prayer and prayer five rak`at. Somebody asked him whether the prayer had been increased." He (the Prophet ) said, "And what is that?" They (the people) replied, "You have prayed five rak`at." Then the Prophet offered two prostrations (of Sahu) after he had finished his prayer with the Taslim.

حَدَّثَنَا حَفْصُ بْنُ عُمَرَ، حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، عَنْ عَبْدِ اللَّهِ، قَالَ صَلَّى بِنَا النَّبِيُّ صلى الله عليه وسلم الظُّهْرَ خَمْسًا فَقِيلَ أَزِيدَ فِي الصَّلاَةِ قَالَ ‏ "‏ وَمَا ذَاكَ ‏" ‏‏.‏ قَالُوا صَلَّيْتَ خَمْسًا‏.‏ فَسَجَدَ سَجْدَتَيْنِ بَعْدَ مَا سَلَّمَ‏.‏