《新唐书·列传·卷七十》
元载当权，暗暗选择才能可以接替自己的人，让他亲近自己。开始选中礼部侍郎刘单，但刘单去世了；又选中吏部侍郎蔡邕，蔡邕因罪贬官；后来选中了杨炎，亲近重用，没人比得上。
载当国，阴择才可代己者，引以自近，初得礼部侍郎刘单，会卒，复取吏部侍郎薛邕，邕坐事贬，后得炎，亲重无比。
Yuan Zai was in power and secretly selected someone whose talent could succeed him and let him approach him. Liu Dan, the minister of Rites, was initially selected, but Liu Dan died; Cai Yong, the minister of officials, was selected again, but Cai Yong was demoted because of his crime; later, Yang Yan was selected and was favored and reused, and no one could surpass him.