《资治通鉴·唐纪·唐纪三十八》
回纥将军车鼻说： 唐朝天子与可汗已经结为兄弟，对雍王来说，可汗是叔父，怎么能不拜舞呢？ 药子昂说： 雍王是天子的长子，如今又为元帅。
回纥将军车鼻曰： 唐天子与可汗约为兄弟，可汗于雍王，叔父也，何得不拜舞 子昂曰： 雍王，天子长子，今为元帅。
The Huihe general, Chenbi, said: The emperor of the Tang Dynasty and the Khan have become brothers, and to Prince Yong the Khan is his uncle. How can he not bow and pay homage? Yao Zi'ang said: Prince Yong is the emperor's eldest son and now also the commander-in-chief.