《资治通鉴·隋纪·隋纪二》
自从北周建立以来，选拔官吏不管品德好坏，及至卢恺代理吏部尚书，与薛道衡一起对官吏的品德加以分别，所以遭到结交朋党的诽谤，以至于获罪。
初，周室以来，选无清浊；及恺摄吏部，与薛道衡等甄别士流，故涉朋党之谤，以至得罪。
Since the establishment of the Northern Zhou Dynasty, the selection of officials did not take into account their moral character. When Lu Kai acted as the Minister in Charge of the Ministry of Officials, he and Xue Daoheng together distinguished between the moral characters of officials, so they were slandered for forming cliques and even convicted of the crime.