《资治通鉴·汉纪·汉纪二十一》
这是理由之六。沿边一带，奴仆婢子忧愁悲苦，想逃亡的人多，都说： 听说匈奴那里快乐，无可奈何的是边塞的监视太紧！ 
又边人奴婢愁苦，欲亡者多，曰： 闻匈奴中乐，无奈候望急何！ 
This is the sixth reason. Along the border, many servants and maids are sad and miserable and want to escape. They all say: “We have heard that it is a happy life there, but we have no choice but to be monitored at the border!”