《后汉书·列传·班彪列传下》
北单于听说汉军出来，派使者到居延塞，想继续来一次呼韩邪故事，朝见天子，请派大使。
北单于闻汉军出，遣使款居延塞，欲修呼韩邪故事，朝见天子，请大使。
When the northern Chanyu heard that the Han army had come out, he sent an envoy to居延塞. He wanted to follow the story of Huhanxie and have an audience with the emperor. He requested the emperor to send an ambassador.