《礼记·祭统》
祭祀中规定，通常由孙子充当代表祖父的尸，这样来讲那个充当尸的人，对于祭祀者来讲是儿子辈，而作为父辈的祭者倒要面朝北去事奉尸，这就是为了让人明白儿子应当如何侍奉父亲。
夫祭之道，孙为王父尸。所使为尸者，于祭者子行也；父北面而事之，所以明子事父之道也。
The sacrifice规定 that the grandson usually acts as the corpse on behalf of the grandfather. In this way, the person who acts as the corpse is the son of the sacrificer, and the sacrificer who is the father should face north to serve the corpse. This is to make people understand how to serve the father.