“The Messenger of Allah ﷺ said: ‘If anyone of you stands after two Rak’ah, if he has not yet stood up fully, let him sit down again, but if he has stood up fully, then let him not sit down, and let him perform two prostrations for forgetfulness (Sahw).’”
قَالَ رَسُولُ اللَّهِ ﷺ إِذَا قَامَ أَحَدُكُمْ مِنَ الرَّكْعَتَيْنِ فَلَمْ يَسْتَتِمَّ قَائِمًا فَلْيَجْلِسْ فَإِذَا اسْتَتَمَّ قَائِمًا فَلاَ يَجْلِسْ وَيَسْجُدْ سَجْدَتَىِ السَّهْوِ