《隋书·列传·卷二十六》
建德中，北周武帝出京巡幸云阳，郭衍在行在所拜谒皇上。当时正议论讨伐北齐，郭衍请求当前锋。
建德中，周武帝出幸云阳，衍朝于行所，时议欲伐齐，衍请为前锋。
In the Jiande years, Emperor Wu of Northern Zhou went out of Beijing to visit Yuyang, where Guo Yan visited the emperor. At that time, they were discussing the attack on Northern Qi, and Guo Yan requested to be in the vanguard.