大般涅槃經義記 8.151

8.151

五破想分別，十二緣法更細推求，心外無法，但是妄想自心所見，如夢所見皆是心起。以心起故，於理本無，名為非有；妄心自現，說為非無。非有、非無名為中道。

Fifth, refuting the conceptual discrimination of thoughts: examining the dharmas of the twelve links even more finely, there are no dharmas outside the mind; they are merely what the deluded thoughts of one's own mind perceive, just as what is seen in a dream all arises from the mind. Because they arise from the mind, in principle they are fundamentally non-existent, which is called non-existent; because the deluded mind manifests them itself, they are spoken of as not non-existent. Being neither existent nor non-existent is called the middle way.