We prayed along with the Messenger of Allah (may peace he upon him) and he committed or omitted (something). Ibrahim said: By Allah, this is a misgiving of mine only. We said: Messenger of Allah, is there something new about the prayer? He (the Holy Prophet) said: No. We told him about what he had done. He (the Holy Prophet) said: When a man commits or omits (something in prayer), he should perform two prostrations, and he then himself performed two prostrations.  

صَلَّيْنَا مَعَ رَسُولِ اللَّهِ ﷺ فَإِمَّا زَادَ أَوْ نَقَصَ قَالَ إِبْرَاهِيمُ وَايْمُ اللَّهِ مَا جَاءَ ذَاكَ إِلاَّ مِنْ قِبَلِي قَالَ فَقُلْنَا يَا رَسُولَ اللَّهِ أَحَدَثَ فِي الصَّلاَةِ شَىْءٌ فَقَالَ لاَ قَالَ فَقُلْنَا لَهُ الَّذِي صَنَعَ فَقَالَ إِذَا زَادَ الرَّجُلُ أَوْ نَقَصَ فَلْيَسْجُدْ سَجْدَتَيْنِ قَالَ ثُمَّ سَجَدَ سَجْدَتَيْنِ  

[Machine] The Messenger of Allahﷺ prayed with us, and sometimes he added and sometimes he omitted. Ibrahim said, "The forgetfulness was a result of my doing." So we asked him, "O Messenger of Allah, did you introduce something new in the prayer?" He said, "What is that?" We said, "You prayed before in such and such a way." He said, "Indeed, I am only a human, I forget just as you forget. So if any one of you forgets something, let him prostrate twice, then turn and prostrate twice."  

صَلَّى بِنَا رَسُولُ اللهِ ﷺ فَإِمَّا زَادَ وَإِمَّا نَقَصَ قَالَ إِبْرَاهِيمُ وَإِنِمَّا جَاءَ نِسْيَانُ ذَلِكَ مِنْ قِبَلِي فَقُلْنَا يَا رَسُولَ اللهِ أَحَدَثَ فِي الصَّلَاةِ شَيْءٌ؟ قَالَ وَمَا ذَاكَ؟ قُلْنَا صَلَّيْتَ قَبْلُ كَذَا وَكَذَا قَالَ إِنَّمَا أَنَا بَشَرٌ أَنْسَى كَمَا تَنْسَوْنَ فَإِذَا نَسِيَ أَحَدُكُمْ فَلْيَسْجُدْ سَجْدَتَيْنِ ثُمَّ تَحَوَّلَ فَسَجَدَ سَجْدَتَيْنِ