Sunan Ibn Majah, Chapter: The Book of the Sunnah

that the Prophet (saw) said: "The likeness of the believer who recites the Quran is that of a citron, the taste and smell of which are good. The likeness of the believer who does not read the Quran is that of a date, the taste of which is good but it has no smell. The likeness of a hypocrite who reads the Qur'an is that of sweet basil, the smell of which is good but its taste is bitter. And the likeness of a hypocrite who does not read the Quran is that of a colocynth (bitter apple), the taste of which is bitter and it has no smell.'" (Sahih)