Sunan an-Nasa'i, Volume 2, Book 13, Hadith 1228 (DarusSalam) ⓘ
It was narrated from Abu Hurairah that: The Messenger of Allah prayed Zuhr with two rak'ahs, then said the salam. They said: "Has the prayer been shortened?" So he stood up and prayed two rak'ahs, then he said the salam, then he prostrated twice.
أَخْبَرَنَا سُلَيْمَانُ بْنُ عُبَيْدِ اللَّهِ، قَالَ حَدَّثَنَا بَهْزُ بْنُ أَسَدٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ سَعْدِ بْنِ إِبْرَاهِيمَ، أَنَّهُ سَمِعَ أَبَا سَلَمَةَ، يُحَدِّثُ عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم صَلَّى صَلاَةَ الظُّهْرِ رَكْعَتَيْنِ ثُمَّ سَلَّمَ فَقَالُوا أَقُصِرَتِ الصَّلاَةُ فَقَامَ وَصَلَّى رَكْعَتَيْنِ ثُمَّ سَلَّمَ ثُمَّ سَجَدَ سَجْدَتَيْنِ .
also referenced under: Hadith 1227 (Reference) & Book 13, Hadith 49 (In-Book)