عَنْ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «خَيْرُكُمْ من تعلم الْقُرْآن وَعلمه» . رَوَاهُ البُخَارِيّ

Ubayy b. Ka‘b said

God’s messenger asked, “Abul Mundhir (this is Ubayy’s Kunya), do you know which verse of God’s Book that you have is greatest?” I replied, “God and His messenger know best.” He repeated his question and I said, “God, there is no god but He, the Living, the Eternal.” Thereupon he struck me on the breast and said, “May knowledge be pleasant for you, Abul Mundhir!” Muslim transmitted it.