《后汉书·列传·王刘张李彭卢列传》
后来匈奴衰弱了，呼韩邪单于归顺于汉，汉为其发兵加以保护，单于世世称臣。
后匈奴中衰，呼韩邪单于归汉，汉为发兵拥护，世世称臣。
Later, Xiongnu grew weak. Chanyu Huhanye surrendered to Han, and Han sent out troops to protect him, hence, Chanyu serve as ministers from generation to generation.