吃人家的嘴软，拿人家的手短

chī rén jiā de zuǐ ruǎn , ná rén jiā de shǒu duǎnchirenjiadezuiruan,narenjiadeshouduan

1. lit. the mouth that has been fed by others is soft, the hand that has received doesn't reach (idiom)
2. fig. one is partial to those from whom presents have been accepted

Study it in Yanamino