What he asked for instead of what he was offered
Jibrīl brought him a choice about how the Qur'an would be recited.
أَسْأَلُ اللَّهَ مُعَافَاتَهُ وَمَغْفِرَتَهُ وَإِنَّ أُمَّتِي لاَ تُطِيقُ ذَلِكَ
He said: I ask Allah for His pardon and His forgiveness, and my nation cannot bear that.
Each time he was offered more, he asked instead for ease on the people who would come after him.
The full narration
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
Source
Ṣaḥīḥ Muslim · 1906
- Agreed upon as authentic (al-Bukhārī / Muslim)