《新唐书·列传·卷四十二》
旧制，宰相议事均在门下省，称为政事堂，长孙无忌身份为司空、房玄龄身份为仆射、魏征身份为太子太师，三人都知门下省之事，到裴炎，以中书令身份执掌政事，所以将政事堂迁到中书省。
旧，宰相议事门下省，号政事堂，长孙无忌以司空、房玄龄以仆射、魏徵以太子太师皆知门下省事，至炎，以中书令执政事笔，故徙政事堂於中书省。
According to the old system, the Prime Minister deliberated matters at the Department of State Affairs, known as the Political Affairs Hall. Changsun Wuji, Fang Xuanling and Wei Zheng respectively held the posts of Minister of Works, Director and Imperial Advisor to the Crown Prince, and all three handled matters at the Department of State Affairs. After Pei Yan became Chancellor of the Secretariat, he was in charge of political affairs. Thus, he relocated the Political Affairs Hall to the Secretariat.