[Machine] Two men from the Ansar read a surah that the Messenger of Allah ﷺ had recited to them, and they used to recite it in prayer. One night, they stood up to pray and were not able to recite it correctly. They went to the Messenger of Allah ﷺ the next morning and told him about it. He said, "Indeed, it is from what has been abrogated and forgotten, so let it be." Al-Zuhri used to recite it as "ma nansakh min ayatin aw nunsiha" with a light kasrah on the noon.  

قَرَأَ رَجُلَانِ مِنَ الْأَنْصَارِ سُورَةً أَقْرَأَهُمَا رَسُولُ اللهِ ﷺ وَكَانَا يَقْرَآنِ بِهِمَا فَقَامَا ذَاتَ لَيْلَةٍ يُصَلِّيَانِ فَلَمْ يَقْدِرَا مِنْهَا عَلَى حَرْفٍ فَأَصْبَحَا غَادِيَيْنِ عَلَى رَسُولِ اللهِ ﷺ فَذَكَرَا لَهُ ذَلِكَ فَقَالَ رَسُولُ اللهِ ﷺ «إِنَّهَا مِمَّا نُسِخَ وَأُنْسِيَ فَالْهَوْا عَنْهَا» فَكَانَ الزُّهْرِيُّ يَقْرَؤُهَا {مَا نَنْسَخْ مِنْ آيَةٍ أَوْ نُنْسِهَا} بِضَمِّ النُّونِ خَفِيفَةً