Correct
来而不往非礼也
/ lái ér bù wǎng fēilǐ yě /
Strokes
Definition
not to reciprocate is against etiquette (classical)/to respond in kind
Example
Definition
it is no propriety not to reciprocate―one should return as good as one receives; it is impolite not to give after receiving; it is impolite not to reciprocate