Miswar ibn Makhramah and Abdur Rahman ibn Abdul Qari said that they heard Umar (RA) ibn al-Khattab say: ‘In the days of the Prophet (SAW) “I passed by Hisham ibn Hakim ibn Hizam while he was reciting surah ai-Furqan. I heard his recital and he was reciting in many readings that Allah’s Messenger (SAW) had not taught me. I very nearly quarrelled with him while he was engaged in salah, but checked myself till he finished. When he turned in salutation, I put his cloak over him and asked him, “Who taught you this surah that I heard you recite (now)?” He said, “Allah’s Messenger (SAW) taught it to me.” I said, “You lie. By Allah, surely Allah’s Messenger (SAW) also taught me this surah.” So, I dragged him to Allah’s Messenger (SAW) and said, “O Messenger of Allah (SAW) , I heard him recite surah al-Furqan in a reading that you have not taught me while you did teach me surah al-Furqan.” So, the Prophet (SAW) said, “Free him, O Umar (RA) . And recite, O Hisham ! So, he recited in the reading that I had heard. The Prophet (SAW) said, “It was revealed in this manner.” Then he asked me to recite. So I did recite as he had taught me and he said, “This is how it was revealed.’ Then he said, “Surely this Quran is revealed in seven readings. So recite that which is easy for you.”
[Ahmed 277,Bukhari 2419,Muslim 818,Nisai 932]