Kural - 100

When pleasant words are easy, bitter words to use,
Is, leaving sweet ripe fruit, the sour unripe to choose

Explanation
To say disagreeable things when agreeable are at hand is like eating unripe fruit when there is ripe.

Tamil Transliteration
Iniya Ulavaaka Innaadha Kooral
Kaniiruppak Kaaikavarn Thatru.