Sahih al-Bukhari 6936
'Umar bin Al-Khattab said:
I heard Hisham bin Al-Hakim reciting Surat Al-Furqan during the lifetime of Allah's Messenger (ﷺ). I listened to his recitation and noticed that he recited it in several different ways which Allah's Messenger (ﷺ) had not taught me. So  I was about to jump over him during his Salat (prayer) but I waited till he finished his Salat (prayer) whereupon I put, either his upper garment or my upper garment around his neck and seized him by it and asked him, "Who has taught you this Surah?" He replied: "Allah's Messenger (ﷺ) has taught it to me." I said (to him), "You have told a lie! By Allah, Allah's Messenger (ﷺ) has taught me this Surah which I have heard you reciting." So I dragged him to the Allah's Messenger (ﷺ). I said: "O Allah's Messenger I have heard this man reciting Surat Al-Furqan in a way in which you have not taught me, and you did teach me Surah Al-Furqan." On that Allah's Messenger (ﷺ) said, "O 'Umar, release him! Recite, O Hisham". So Hisham recited before him in the way as I heard him reciting. Allah's Messenger (ﷺ) said, "It has been revealed like this." Then Allah's Messenger (ﷺ) said, "Recite, O 'Umar" So recited it. The Prophet (ﷺ) said, "It has been revealed like this." And then he added, "This Qur'an has been revealed to be recited in seven different ways, so recite it whichever way is easier for you."
قَالَ أَبُو عَبْدِ اللَّهِ وَقَالَ اللَّيْثُ حَدَّثَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي عُرْوَةُ بْنُ الزُّبَيْرِ، أَنَّ الْمِسْوَرَ بْنَ مَخْرَمَةَ، وَعَبْدَ الرَّحْمَنِ بْنَ عَبْدٍ الْقَارِيَّ، أَخْبَرَاهُ أَنَّهُمَا، سَمِعَا عُمَرَ بْنَ الْخَطَّابِ، يَقُولُ سَمِعْتُ هِشَامَ بْنَ حَكِيمٍ، يَقْرَأُ سُورَةَ الْفُرْقَانِ فِي حَيَاةِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَاسْتَمَعْتُ لِقِرَاءَتِهِ، فَإِذَا هُوَ يَقْرَؤُهَا عَلَى حُرُوفٍ كَثِيرَةٍ لَمْ يُقْرِئْنِيهَا رَسُولُ اللَّهِ صلى الله عليه وسلم كَذَلِكَ، فَكِدْتُ أُسَاوِرُهُ فِي الصَّلاَةِ فَانْتَظَرْتُهُ حَتَّى سَلَّمَ، ثُمَّ لَبَّبْتُهُ بِرِدَائِهِ أَوْ بِرِدَائِي فَقُلْتُ مَنْ أَقْرَأَكَ هَذِهِ السُّورَةَ قَالَ أَقْرَأَنِيهَا رَسُولُ اللَّهِ صلى الله عليه وسلم قُلْتُ لَهُ كَذَبْتَ فَوَاللَّهِ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم أَقْرَأَنِي هَذِهِ السُّورَةَ الَّتِي سَمِعْتُكَ تَقْرَؤُهَا‏.‏ فَانْطَلَقْتُ أَقُودُهُ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقُلْتُ يَا رَسُولَ اللَّهِ إِنِّي سَمِعْتُ هَذَا يَقْرَأُ بِسُورَةِ الْفُرْقَانِ عَلَى حُرُوفٍ لَمْ تُقْرِئْنِيهَا، وَأَنْتَ أَقْرَأْتَنِي سُورَةَ الْفُرْقَانِ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أَرْسِلْهُ يَا عُمَرُ، اقْرَأْ يَا هِشَامُ ‏"‏‏.‏ فَقَرَأَ عَلَيْهِ الْقِرَاءَةَ الَّتِي سَمِعْتُهُ يَقْرَؤُهَا‏.‏ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ هَكَذَا أُنْزِلَتْ ‏"‏‏.‏ ثُمَّ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ اقْرَأْ يَا عُمَرُ ‏"‏‏.‏ فَقَرَأْتُ فَقَالَ ‏"‏ هَكَذَا أُنْزِلَتْ ‏"‏‏.‏ ثُمَّ قَالَ ‏"‏ إِنَّ هَذَا الْقُرْآنَ أُنْزِلَ عَلَى سَبْعَةِ أَحْرُفٍ فَاقْرَءُوا مَا تَيَسَّرَ مِنْهُ ‏"‏‏.‏