Imam Bukhari narrates: Uthman narrated a hadith to us, he said: Jarir narrated a hadith to us from Mansur, from Ibrahim, from Alqamah, he said: ʿAbdullāh ibn Masʿūd (may Allāh be pleased with him) states that
the Prophet ﷺ led the prayer. Ibrahim said: I do not know whether he added something or reduced something in that prayer. So when he gave the salām, it was said to him: O Messenger of Allāh! Has some new command been revealed in the prayer? He asked: What is the reason for that? The Companions said: You prayed like this and like this. He turned his feet, faced the qiblah, and made two prostrations, then gave the salām. Then, facing us, he said: If some new command had been revealed in the prayer, I would have informed you of it. But I am only a human being like you. I forget just as you forget. So when I forget, remind me. And when any of you has a doubt in his prayer, he should think carefully and find out the correct thing, then complete his prayer, then give the salām and make two prostrations.
حَدَّثَنَا عُثْمَانُ، قَالَ حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، قَالَ قَالَ عَبْدُ اللَّهِ صَلَّى النَّبِيُّ صلى الله عليه وسلم ـ قَالَ إِبْرَاهِيمُ لاَ أَدْرِي زَادَ أَوْ نَقَصَ ـ فَلَمَّا سَلَّمَ قِيلَ لَهُ يَا رَسُولَ اللَّهِ، أَحَدَثَ فِي الصَّلاَةِ شَىْءٌ قَالَ " وَمَا ذَاكَ ". قَالُوا صَلَّيْتَ كَذَا وَكَذَا. فَثَنَى رِجْلَيْهِ وَاسْتَقْبَلَ الْقِبْلَةَ، وَسَجَدَ سَجْدَتَيْنِ ثُمَّ سَلَّمَ، فَلَمَّا أَقْبَلَ عَلَيْنَا بِوَجْهِهِ قَالَ " إِنَّهُ لَوْ حَدَثَ فِي الصَّلاَةِ شَىْءٌ لَنَبَّأْتُكُمْ بِهِ، وَلَكِنْ إِنَّمَا أَنَا بَشَرٌ مِثْلُكُمْ، أَنْسَى كَمَا تَنْسَوْنَ، فَإِذَا نَسِيتُ فَذَكِّرُونِي، وَإِذَا شَكَّ أَحَدُكُمْ فِي صَلاَتِهِ فَلْيَتَحَرَّى الصَّوَابَ، فَلْيُتِمَّ عَلَيْهِ ثُمَّ يُسَلِّمْ، ثُمَّ يَسْجُدْ سَجْدَتَيْنِ ".
Reference: Sahih Al Bukhari 401