one good turn deserves another
以德报德；善有善报
口语·表达互惠互助
英文释义
an act of kindness should be reciprocated with another act of kindness
例句
You helped me with my project last week, so I'll cover your shift today. One good turn deserves another.
典故来源
源自16世纪英国谚语，强调善行应得到善行的回报，类似于中国的“投桃报李”。