投桃报李

tóu táo bào lǐ

to return a favour; friendly give and take

Character by character

投tóu
throw

桃táo
peach

报bào
repay

李lǐ
plum

你帮我搬了家，我请你吃饭，这叫投桃报李。

You helped me move, so I am buying you dinner: one good turn deserves another.

Tone: positive (praise).

From 《大雅·抑》: 投我以桃，报之以李. Of an exchange of favours between friends, firms or countries; 《木瓜》 says the same with a quince and a piece of jade.

Learn this in Lesson 230 · HSK 9+: 诗经：最早的歌 (The Book of Songs)

A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.