What should a person do if he says the taslim following two rak'ahs by mistake and then
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 .
It was narrated from Abu Hurairah that: The Messenger of Allah (ﷺ) 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.