Keep your words sweet – you may have to eat them sometime.
There is one very similar subhashita in Sanskrit, which always been my favorite.
प्रियवाक्यप्रदानेन सर्वे तुश्यंति जंतवः | तस्मात्तदेव वक्तव्यं वचने का दरीद्रता ||
(To read: priyavAkyapradAnEna sarvE tushanti jantavah tasmattadEva vaktavyam vachanE ka darIdratA )
All living creatures love listening to you, if you talk sweet. So why poverty of sweet words ?