《礼记·明堂位》
所以周公辅佐武王以讨伐纣王。武王驾崩，嗣君成王年龄尚小，于是由周公摄政，代行天子职务，以治理天下。
昔殷纣乱天下，脯鬼侯以飨诸侯。是以周公相武王以伐纣。
Therefore, the Duke of Zhou assisted King Wu in punishing King Zhou. After King Wu passed away, the successor King Cheng was still young, so the Duke of Zhou took over the regency and carried out the duty of the emperor to govern the world.