《汉书·传·蒯伍江息夫传》
正赶上单于应当来朝拜天子，单于派使者来说单于生病了，想第二年入朝参见皇帝。
会单于当来朝，遣使言病，愿朝明年。
Coincidentally, it was time for the Chanyu to come and pay homage to the Emperor, but the Chanyu sent a messenger to say that he had fallen ill and wanted to come to court to pay his respects to the Emperor the following year.