Hadith

‘Narrated ‘Abdullah bin ‘Abbas: Allah’s apostle 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’. [Bukhari, VI No. 513.]
On another occasion, ‘Umar complained to the Prophet that Hisham had recited Sura al-furqan in a way different from what ‘Umar had heard from the Prophet, but the Prophet said: ‘… this Qur’an has been revealed to be recited in seven different ways, so recite of it whichever is easier for you’. [Bukhari, VI No. 514.]

 

From: Translation of Sahih Muslim