逢人且说三分话,未可全抛一片心 When meeting people, say only three tenths of what is on the mind. Do not throw out the whole heart. (Words to Broaden Wisdom, a collection of old sayings)
酒逢知己千杯少,话不投机半句多 With a close friend, a thousand cups of wine are too few. When the talk does not suit, half a sentence is too many.