《旧唐书·列传·卷一百三十四》
十二月，代宗车驾回到京城，程元振披麻戴孝地坐在车子里，混入京城，以谋划再度任职进用。
十二月，车驾还京。元振服缞麻于车中，入京城，以规任用。
In December, Emperor Daizong returned to the imperial capital in a carriage. Cheng Yuanzhen dressed in mourning clothes and sat in the carriage. He secretly entered the imperial capital, plotting to be reinstated.