Ibn Majah: Hadith 214

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