Let’s listen to Ibn ‘Arabi (1165-1240) from his Fusus al-hikam as he discusses panentheism or, what is the same thing, a core teaching of nondual metaphysics:

The world is illusory: it has no real existence. This is what is meant by imagination (khayal). You have been made to imagine that the world is something separate and independently real, outside of the Absolute. But in reality it is not so. Do you not see that in the world of sensory things a shadow is attached to the person from whom it originates and that it is impossible to separate a thing from its essence? Therefore know thy own essence and who thou art, what thy inmost nature is and what thy relation is to the Absolute. Know in what respect thou art the Absolute, in what respect the world, and in what respect “other” (than God), “different,” etc. And here it is that “knowers” become ranked according to degrees.

William C. Chittick, The Sufi Doctrine of Rumi: Illustrated Edition, p. 30

Or in William Chittick’s apt summary: “There is no real but the Real.”