Добрые слова лучше мягкого пирога

See Ласковое слово не трудно, да споро (Л)

Var.: Добрые слова лучше сладкого пирога

Cf: All doors /are/ open to courtesy (Br.). Fair and soft (softly) goes far / in a day/ (Br.). Fair and softly go far in a day (Am.). Fair words make the pot boil (Am.). A kind word goes a long way (Am.). A kind word is never lost (Br.). Mouth civility is no great pains but may turn to a good account (Br.)