Narrated Umar bin Khattab:

I heard Hisham bin Hakim bin Hizam reciting Surat-al-Furqan during the lifetime of Allah's Apostle, and I listened to his recitation and noticed that he recited it in several ways which Allah's Apostle had not taught me. So I was on the point of attacking him in the prayer, but I waited till he finished his prayer, and then I seized him by the collar and said, "Who taught you this Surah which I have heard you reciting?" He replied, "Allah's Apostle taught it to me." I said, "You are telling a lie;
By Allah! Allah's Apostle taught me (in a different way) this very Surah which I have heard you reciting." So I took him, leading him to Allah's Apostle and said, "O Allah's Apostle! I heard this person reciting Surat-al-Furqan in a way that you did not teach me, and you have taught me Surat-al-Furqan." The Prophet ﷺ said, "O Hisham, recite!" So he recited in the same way as I heard him recite it before. On that Allah's Apostle ﷺ said, "It was revealed to be recited in this way." Then Allah's Apostle ﷺ said, "Recite, O 'Umar!" So I recited it as he had taught me. Allah's Apostle then said, "It was revealed to be recited in this way." Allah" Apostle added, "The Quran has been revealed to be recited in several different ways, so recite of it that which is easier for you."

حَدَّثَنَا أَبُو الْيَمَانِ، أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ، قَالَ أَخْبَرَنِي عُرْوَةُ، عَنْ حَدِيثِ الْمِسْوَرِ بْنِ مَخْرَمَةَ، وَعَبْدِ الرَّحْمَنِ بْنِ عَبْدٍ الْقَارِيِّ، أَنَّهُمَا سَمِعَا عُمَرَ بْنَ الْخَطَّابِ، يَقُولُ سَمِعْتُ هِشَامَ بْنَ حَكِيمِ بْنِ حِزَامٍ، يَقْرَأُ سُورَةَ الْفُرْقَانِ فِي حَيَاةِ رَسُولِ اللَّهِ ﷺ فَاسْتَمَعْتُ لِقِرَاءَتِهِ فَإِذَا هُوَ يَقْرَؤُهَا عَلَى حُرُوفٍ كَثِيرَةٍ لَمْ يُقْرِئْنِيهَا رَسُولُ اللَّهِ ﷺ فَكِدْتُ أُسَاوِرُهُ فِي الصَّلاَةِ فَانْتَظَرْتُهُ حَتَّى سَلَّمَ فَلَبَبْتُهُ فَقُلْتُ مَنْ أَقْرَأَكَ هَذِهِ السُّورَةَ الَّتِي سَمِعْتُكَ تَقْرَأُ قَالَ أَقْرَأَنِيهَا رَسُولُ اللَّهِ ﷺ. فَقُلْتُ لَهُ كَذَبْتَ فَوَاللَّهِ إِنَّ رَسُولَ اللَّهِ ﷺ لَهُوَ أَقْرَأَنِي هَذِهِ السُّورَةَ الَّتِي سَمِعْتُكَ، فَانْطَلَقْتُ بِهِ إِلَى رَسُولِ اللَّهِ ﷺ أَقُودُهُ فَقُلْتُ يَا رَسُولَ اللَّهِ إِنِّي سَمِعْتُ هَذَا يَقْرَأُ سُورَةَ الْفُرْقَانِ عَلَى حُرُوفٍ لَمْ تُقْرِئْنِيهَا وَإِنَّكَ أَقْرَأْتَنِي سُورَةَ الْفُرْقَانِ. فَقَالَ " يَا هِشَامُ اقْرَأْهَا ". فَقَرَأَهَا الْقِرَاءَةَ الَّتِي سَمِعْتُهُ فَقَالَ رَسُولُ اللَّهِ ﷺ " هَكَذَا أُنْزِلَتْ ". ثُمَّ قَالَ " اقْرَأْ يَا عُمَرُ ". فَقَرَأْتُهَا الَّتِي أَقْرَأَنِيهَا، فَقَالَ رَسُولُ اللَّهِ ﷺ " هَكَذَا أُنْزِلَتْ ". ثُمَّ قَالَ رَسُولُ اللَّهِ ﷺ " إِنَّ الْقُرْآنَ أُنْزِلَ عَلَى سَبْعَةِ أَحْرُفٍ فَاقْرَءُوا مَا تَيَسَّرَ مِنْهُ ".