(5) باب أُنْزِلَ الْقُرْآنُ عَلَى سَبْعَةِ أَحْرُفٍ
Narrated `Abdullah bin `Abbas:
Allah's Messenger (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."
Reference: Sahih al-Bukhari 4991
In-book reference: Book 66, Hadith 13
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 6, Book 61, Hadith 513