(literary) to put aside hatred or personal enmity in order to use someone's talents, referring to the story from the Zuo Zhuan where Qi Huan Gong forgave 管仲 guǎn​zhòng for shooting his belt buckle and later appointed him prime minister

(literary) a person who was once a traitor or a personal enemy but is now valued, alluding to the assassination attempt by 管仲 guǎn​zhòng against the future Duke Huan of Qi