Sahih Bukhari – Hadith No : 7336

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.

Hadith In Arabic Text :

حدثنا حفص بن عمر، حدثنا شعبة، عن الحكم، عن إبراهيم، عن علقمة، عن عبد الله، قال صلى بنا النبي صلى الله عليه وسلم الظهر خمسا فقيل أزيد في الصلاة قال ‏”‏ وما ذاك ‏”‏‏.‏ قالوا صليت خمسا‏.‏ فسجد سجدتين بعد ما سلم‏.‏

Chapter : Accepting Information Given by a Truthful Person – كتاب أخبار الآحاد