桀犬吠尧

jiéquǎn-fèiyáo

[The dog of Jie barked at Yao-utterly unscrupulous in its zeal to serve its master] 《汉书·邹阳传》: "桀之犬可使吠尧", 后以"桀犬吠尧"比喻走狗一心为它的主子效劳, 也比喻各为其主