《旧唐书·列传·卷一百一十四》
朕本因丹王以下四人，院中均无侍奉者。朕令于乐工之中及民间有情愿者，付给丰厚钱帛，只征选四人，四位侯王各予一人。
朕缘丹王已下四人，院中都无侍者，朕令于乐工中及闾里有情愿者，厚其钱帛，只取四人，四王各与一人。
"I originally ordered the selection of four people because Prince Dan and the other three had no attendants in their palaces. I ordered that, from the musicians and those from the people who were willing, they should be given generous money and silk and that only four should be selected and each of the four princes should receive one."