人无横财不富，马无夜草不肥

rén wú hèng cái bù fù , mǎ wú yè cǎo bù féirenwuhengcaibufu,mawuyecaobufei

1. (saying) a person cannot become wealthy without windfall profits (or ill-gotten gains etc), just as a horse cannot get fat without night feed

Study it in Yanamino