中山狼传/ 中山狼傳 zhōngshānlángzhuàn The Wolf of Zhongshan
A Ming dynasty fable by 马中锡 mǎzhōngxī about the scholar 东郭先生 dōngguōxiānsheng and an ungrateful wolf who attempts to eat his rescuer; used to describe those who return kindness with betrayal.