Mastery Over the Qir’aat
One can gauge an understanding of Hazrat Ubayy bin Kaab’s (ra) mastery over the qir‘aat [readings of the Holy Quran] that the Holy Prophet (sa) himself would recite the entire Holy Quran to him. Thus, the year in which the Holy Prophet (sa) passed away, he recited the Quran to Hazrat Ubayy (ra) and stated, “Gabriel has told me that I should recite the Quran to Ubayy.”
(Sheikh Shah Moinuddin Ahmad Nadvi, Siyar al-Sahabah, Vol. 3 [Karachi, Pakistan: Dar al-Ishaah Urdu Bazar, 2004] 149)
And so, the Holy Prophet (sa) recited the Holy Quran to Hazrat Ubayy (ra).