桀犬吠尧jié quǎn fèi yáo

《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。

英The dog of Jie barked at Yao-utterly unscrupulous in its zeal to serve its master;