Messenger of Allah ﷺ said, "Gabriel recited the Qur'an to me in one way. Then I requested him (to read it in another way), and continued asking him to recite it in other ways, and he recited it in several ways till he ultimately recited it in seven different ways."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ أَقْرَأَنِي جِبْرِيلُ عَلَى حَرْفٍ فَرَاجَعْتُهُ فَلَمْ أَزَلْ أَسْتَزِيدُهُ وَيَزِيدُنِي حَتَّى انْتَهَى إِلَى سَبْعَةِ أَحْرُفٍ  

I heard Hisham bin Hakim reciting Surat Al-Furqan during the lifetime of Messenger of Allah ﷺ and I listened to his recitation and noticed that he recited in several different ways which Messenger of Allah ﷺ had not taught me. I was about to jump over him during his prayer, but I controlled my temper, and when he had completed his prayer, I put his upper garment around his neck and seized him by it and said, "Who taught you this Sura which I heard you reciting?" He replied, "Messenger of Allah ﷺ taught it to me." I said, "You have told a lie, for Messenger of Allah ﷺ has taught it to me in a different way from yours." So I dragged him to Messenger of Allah ﷺ and said (to Messenger of Allah ﷺ), "I heard this person reciting Surat Al-Furqan in a way which you haven't taught me!" On that Allah's Apostle said, "Release him, (O ʿUmar!) Recite, O Hisham!" Then he recited in the same way as I heard him reciting. Then Messenger of Allah ﷺ said, "It was revealed in this way," and added, "Recite, O ʿUmar!" I recited it as he had taught me. Messenger of Allah ﷺ then said, "It was revealed in this way. This Qur'an has been revealed to be recited in seven different ways, so recite of it whichever (way) is easier for you (or read as much of it as may be easy for you).  

سَمِعْتُ هِشَامَ بْنَ حَكِيمٍ يَقْرَأُ سُورَةَ الْفُرْقَانِ فِي حَيَاةِ رَسُولِ اللَّهِ ﷺ فَاسْتَمَعْتُ لِقِرَاءَتِهِ فَإِذَا هُوَ يَقْرَأُ عَلَى حُرُوفٍ كَثِيرَةٍ لَمْ يُقْرِئْنِيهَا رَسُولُ اللَّهِ ﷺ فَكِدْتُ أُسَاوِرُهُ فِي الصَّلاَةِ فَتَصَبَّرْتُ حَتَّى سَلَّمَ فَلَبَّبْتُهُ بِرِدَائِهِ فَقُلْتُ مَنْ أَقْرَأَكَ هَذِهِ السُّورَةَ الَّتِي سَمِعْتُكَ تَقْرَأُ قَالَ أَقْرَأَنِيهَا رَسُولُ اللَّهِ ﷺ فَقُلْتُ كَذَبْتَ فَإِنَّ رَسُولَ اللَّهِ ﷺ قَدْ أَقْرَأَنِيهَا عَلَى غَيْرِ مَا قَرَأْتَ فَانْطَلَقْتُ بِهِ أَقُودُهُ إِلَى رَسُولِ اللَّهِ ﷺ فَقُلْتُ إِنِّي سَمِعْتُ هَذَا يَقْرَأُ بِسُورَةِ الْفُرْقَانِ عَلَى حُرُوفٍ لَمْ تُقْرِئْنِيهَا فَقَالَ رَسُولُ اللَّهِ ﷺ أَرْسِلْهُ اقْرَأْ يَا هِشَامُ فَقَرَأَ عَلَيْهِ الْقِرَاءَةَ الَّتِي سَمِعْتُهُ يَقْرَأُ فَقَالَ رَسُولُ اللَّهِ ﷺ كَذَلِكَ أُنْزِلَتْ ثُمَّ قَالَ اقْرَأْ يَا عُمَرُ فَقَرَأْتُ الْقِرَاءَةَ الَّتِي أَقْرَأَنِي فَقَالَ رَسُولُ اللَّهِ ﷺ كَذَلِكَ أُنْزِلَتْ إِنَّ هَذَا الْقُرْآنَ أُنْزِلَ عَلَى سَبْعَةِ أَحْرُفٍ فَاقْرَءُوا مَا تَيَسَّرَ مِنْهُ