《资治通鉴·魏纪·魏纪四》
曹植又上书说： 从前，汉文帝众代国出发，怀疑朝廷肆生事变，宋昌说： 京城内有朱虚侯、东牟侯这些皇亲，外有齐、楚、淮南、琅琊各封国，都是磐石般的皇族，望君王不要怀疑。 
植复上疏曰： 昔汉文发代，疑朝有变，宋昌曰： 内有硃虚、东牟之亲，外有齐、楚、淮南、琅邪，此则磐石之宗，愿王勿疑。 
Cao Zhi wrote again and said: In the past, Emperor Wen of the Han Dynasty departed from the state of Zhongdai and suspected that the imperial court was causing chaos. Song Chang said: There are imperial relatives such as Zhu Xuhou and Dongmuhou in the capital, and there are fiefdoms such as Qi, Chu, Huainan, and Langya outside. The imperial family is as solid as a rock, and I hope the king will not doubt it.