《旧唐书·本纪·卷十四》
他们因参加平凉县的盟会而滞留在吐蕃，过了很长时间才回国，因为熟悉吐蕃的情况，朝廷不愿让他们到外边去，所以把他们软禁在宫庭拘留所，直到这时才释放他们。
平凉之盟陷蕃。久之得还，以习蕃中事，不欲令出外，故囚之仗内，至是方释之。
They had been stranded in Tubo because they had participated in the alliance in Pingliang County. It took a long time for them to return to China. Because they were familiar with the situation in Tubo, the court did not want them to go abroad, so they were kept in the detention center of the palace until they were released at this time.