سنن أبي داود

'Umar b. al-Khattab said: I heard Hisham b. Hakim (b. Hizam) reciting Surah al-Furqan in a different manner from my way of reciting, and the Messenger of Allah (ﷺ) had taught me to recite it. I nearly spoke sharply to him, but I delayed till he had finished. Then I caught his cloak at the neck, and I brought him to the Messenger of Allah (ﷺ). I said: Messenger of Allah, I heard this man reciting Surah al-Furqan in a manner different from that in which you taught me to recite it. The Messenger of Allah (ﷺ) the told him to recite it. He then recited in the manner I heard him recite. The Messenger of Allah (ﷺ) said: Thus was it sent down. He then said to me: Recite, I recited (it). He then said: Thus was it sent down. He said: The Qur'an was sent down in seven modes of reading, so recite according to what comes most easily.