魚心あれば水心
Meanings
1
kindness begets kindness; you scratch my back and I'll scratch yours
Proverb meaning that if you show goodwill to others, they will respond in kind. The literal image is that if a fish is kind to the water, the water will be kind to the fish.
As the saying goes, kindness begets kindness; if you are kind to others, they will be kind to you in return.