The Messenger of Allah ﷺ prayed Zuhr then he turned to face them and they said: 'Has there been some change concerning the prayer?' He said: 'Why are you asking?' They told him what he had done, so he turned back toward the Qiblah and prostrated twice. Then he said the salam and turned to face them and said: 'I am only human, I forget as you forget, so if I forget, then remind me.' And he said: 'If there had been some change concerning the prayer I would have told you.' And he said: 'If one of you is not sure about his prayer, let him estimate what is closest to what is correct, then let him complete it on that basis, then prostrate twice.' (Using translation from Nasāʾī 1244)
أَنَّ رَسُولَ اللهِ ﷺ صَلَّى صَلَاةَ الظُّهْرِ ثُمَّ أَقْبَلَ عَلَيْهِمْ بِوَجْهِهِ فَقَالُوا أَحْدَثَ فِي الصَّلَاةِ حَدَثٌ قَالَ «وَمَا ذَاكَ» فَأَخْبَرُوهُ بِصَنِيعِهِ فَثَنَى رِجْلَهُ وَاسْتَقْبَلَ الْقِبْلَةَ فَسَجَدَ سَجْدَتَيْنِ ثُمَّ سَلَّمَ ثُمَّ أَقْبَلَ عَلَيْهِمْ بِوَجْهِهِ فَقَالَ «إِنَّمَا أَنَا بِشْرٌ مِثْلُكُمْ أَنْسَى كَمَا تَنْسَوْنَ فَإِذَا نَسِيتُ فَذَكِّرُونِي» قَالَ وَقَالَ «لَوْ كَانَ حَدَثَ فِي الصَّلَاةِ حَدَثٌ أَنْبَأْتُكُمْ» قَالَ وَقَالَ «إِذَا أَوْهَمَ أَحَدُكُمْ فِي صَلَاةٍ فَلْيَتَحَرَّ أَقْرَبَ ذَلِكَ مِنَ الصَّوَابِ ثُمَّ لِيُتِمَّ عَلَيْهِ ثُمَّ لِيَسْجُدْ سَجْدَتَيْنِ»