急流勇退 jíliú-yǒngtuì
[resolutely retire at the height of one's official career;draw back wissly in face of overwhelming odds] 舟行急流之中而勇于自退,比喻为官正在得势的时候退下来
火色上腾虽有数,急流勇退岂无人。——宋· 苏轼《赠善相程杰》