Sahih Bukhari Volume 7, Book 65, Hadith Number 338.

Narrated By Abu Musa Al-Ash’ari : Allah’s Apostle said, “The example of a Believer who recites the Quran, is that of a citron which smells good and tastes good; And the example of a Believer who does not recite the Quran, is that of a date which has no smell but tastes sweet; and the example of a hypocrite who recites the Quran, is that of an aromatic plant which smells good but tastes bitter; and the example of a hypocrite who does not recite the Quran, is that of a colocynth plant which has no smell and is bitter in taste.”