صحيح مسلم

Ubayy b. Ka'b reported that the Messenger of Allah (ﷺ) was near the tank of Banu Ghifar that Gabriel came to him and said: Allah has commanded you to recite to your people the Qur'an in one dialect. Upon this he said: I ask from Allah pardon and forgiveness. My people are not capable of doing it. He then came for the second time and said: Allah has commanded you that you should recite the Qur'an to your people in two dialects. Upon this he (the Holy prophet) again said: I seek pardon and forgiveness from Allah, my people would not be able to do so. He (Gabriel) came for the third time and said: Allah has commanded you to recite the Qur'an to your people in three dialects. Upon this he said: I ask pardon and forgiveness from Allah. My people would not be able to do it. He then came to him for the fourth time and said: Allah has commanded you to recite the Qur'an to your people in seven dialects, and in whichever dialect they would recite, they would be right.