Sahih Bukhari | Volume 6 | Hadith Number 527

Narrated by Ibn 'Abbas
Umar said, "Ubai was the best of us in the recitation (of the Qur'an) yet we leave some of what he recites." Ubai says, "I have taken it from the mouth of Allah's Apostle and will not leave for anything whatever." But Allah said, "None of Our Revelations do We abrogate or cause to be forgotten but We substitute something better or similar." (2:106)