Yahya related to me from Malik from Ibn Shihab from Urwa ibn az-Zubayr that Abd ar-Rahman ibn Abd al-Qari said that he had heard Umaribn al-Khattab say, "I heard Hisham ibn Hakim ibn Hizam reciting Suratal-Furqan (Sura 25) differently from me, and it was the Messenger ofAllah, may Allah bless him and grant him peace, who had recited it tome. I was about to rush up to him but I granted him a respite until hehad finished his prayer. Then I grabbed him by his cloak and took himto the Messenger of Allah, may Allah bless him and grant him peace,and said, 'Messenger of Allah, I heard this man reciting Surat al-Furqan differently from the way you recited it to me.' The Messengerof Allah, may Allah bless him and grant him peace, said, 'Let him go.'Then he said, 'Recite, Hisham,' and Hisham recited as I had heard himrecite. The Messenger of Allah, may Allah bless him and grant himpeace, said, 'It was sent down like that.' Then he said to me,'Recite' and I recited the sura, and he said, 'It was sent down likethat. This Qur'an was sent down in seven (different) ways, so recitefrom it whatever is easy for you .' "
USC-MSA web (English) reference: Book 15, Hadith 5
Arabic reference: Book 15, Hadith 477