注維摩詰經 3.175

3.175

肇曰：尋知其本也。夫執本以知其末、守母以見其子。佛言眾生垢淨皆由心起，求心之本不在三處。心既不在，罪垢可知也。

[Seng]zhao says: "Investigate to know its root. One grasps the root to know the branches; one holds to the mother to see the child. The Buddha said that the defilement and purity of sentient beings all arise from the mind. If one seeks the root of the mind, it is not in the three places. Since the mind is not there, sinful defilement can be understood [in the same way]."