《周礼·春官宗伯·典命&职丧》
有大丧，已经确定了葬期，就请求开始度量挖墓穴的地方，葬毕祭墓地就充当尸。
大丧，既有日，请度甫，遂为之尸。
In the event of a major bereavement, the burial date is set, and then the measurement of the tomb excavation is requested. When the burial is completed, the mourner becomes the corpse.