狗咬呂洞賓，不識好人心 [－－吕－宾－－识－－－]

Jyutping gau2 ngaau5 leoi5 dung6 ban1 , bat1 sik1 hou2 jan4 sam1
Pinyin gǒu yǎo lǚ dòng bīn , bù shí hǎo rén xīn

Definitions (CC-CEDICT)
  1. a dog biting Lü Dongbin (idiom)
  2. to ill reward a person's kindness