Ubayy b. Kā'b said

When I was in the mosque a man entered and prayed and recited in a manner to which I objected. Afterwards a man entered and recited in a manner different from the other. When we had finished the prayer we all went to visit Allah's Messenger ﷺ, and I said, “This man recited in a manner to which I objected and the other entered and recited in a manner different from his.” The Prophet (ﷺ) then commanded them to recite, and when they had done so he expressed approval of both of them. This made me inclined to tell him he was wrong, even to an extent I had never reached in the pre-Islamic period; and when Allah's Messenger ﷺ noticed how I was affected he gave me a pat on the chest, whereupon I broke into a sweat and was filled with fear as though I were looking at Allah. He then said to me, “A message was sent to me, Ubayy, to recite the Qur’ān in one mode, but when I replied that I wished matters to be made easy for my people, a second message instructed me to recite it in two modes. Again I replied that I wished matters to be made easy for my people, and a third message instructed me to recite it in seven modes, I being told at the same time that I might ask something for each reply I had received. I therefore said, ‘O Allah, forgive my people. O Allah, forgive my people;’ and I have delayed the third request till the day when all creatures, even including Abraham, seek my intercession." Muslim transmitted it.