The Messenger of Allah ﷺ said, "Jibreel recited the Quran to me in one mode, and I asked him to recite it again. I kept asking him for more, and he kept granting me more, until it reached seven modes."
أن رسول الله ﷺ قال: أقرأني جبريل على حرف فراجعته، فلم أزل أستزيده ويزيدني حتى انتهى إلى سبعة أحرف.
Bukhari related it in the Excellences of the Quran (5060, 5061), and Muslim in the Prayer of Travelers (818:272), both of them by way of Ibn Shihab, who said, Ubaydullah bin Abdullah bin Utba told me that Ibn Abbas told him, and he related it.Muslim added at the end, Ibn Shihab said, "It has reached me that those seven modes concern a matter that remains one and the same, with no difference regarding what is permitted or forbidden."