《后汉书·本纪·显宗孝明帝纪》
常山三老对明帝说 ：帝在元氏诞生，请求对这里有所优待，减免赋税。 明帝下诏说： 丰、沛、济阳，是祖先命创立帝业的地方，加恩报德，是很合适的。
常山三老言于帝曰： 上生于元氏，愿蒙优复。 诏曰： 丰、沛、济阳，受命所由，加恩报德，适其宜也。
The Three Elders of Changshan said to Emperor Ming: "The emperor was born in Yuan clan, and he requested to give this place preferential treatment and reduce taxes." Emperor Ming decreed: "Feng, Pei, and Jiyang are the places where ancestors ordered to establish the imperial cause, it is appropriate to show favor and repay virtue."