《北齐书·列传·卷十二》
皇帝又派冯子琮召高俨，高俨推辞说： 和士开以前确实应该死一万次，图谋废掉皇帝，剃掉家家的头发让她作尼姑，所以聚集兵马打算居留在孙凤珍的住宅，臣为此假藉诏令杀了他。
帝又使冯子琮召俨，俨辞曰： 士开昔来实合万死，谋废至尊，剃家家头使作阿尼，故拥兵马欲坐着孙凤珍宅上，臣为是矫诏诛之。
The emperor sent Feng Zizong to summon Gao Yan again, but Gao Yan declined, saying: He Shikai should have been killed ten thousand times before. He plotted to abolish the emperor, shave all the women's hair and make them nuns, so I gathered troops and planned to stay at Sun Fengzhen's residence. I killed him under the false pretense of an imperial edict.