ॐ ईशावास्यमिदं सर्वं यत्किञ्च जगत्यां जगत्
तेन त्यक्तेन भुञ्जीथा: मा गृधः कस्यस्विद्धनम् ||
All this is pervaded by the Lord, whatever is moving (and not moving) in this world. By such renunciation enjoy (or protect). Do not covet the wealth of anyone.
Vasyam or avasyam means fit to be dwelt by or clothed by or covered over by. The universe is to be covered over by the consciousness of God. It means that God indwells every being of the universe. But this indwelling does not in any way create a distinction between the indweller and the indwelled. The Lord exists as the innermost Self of all. The Self, however, cannot pervade itself. Pervasion, here, means existence. The universe in essence is the truth of God Himself. It does not exist as an object to be covered over by God, like cloth, etc. There is nothing in this universe which can have any value or being without the existence of God. This is to say that God is the sole existence.
It also means that one has to fill the whole universe with the consciousness of Divinity. Divinity should be felt as the pratyagatman or the Inner Self of oneself. This is a clue to meditation on Brahman, also. One should assert that the whole existence is, in its objective form, unreal and that oneself in fact is the essential atman existing as the basis and the truth of everything. This is to assert that one's Self is the Supreme Lord, not merely pervading everything, but existing as the only reality.
Even as a scented stick begins to give out its fragrance when the external fungus growing over it is rubbed out, the light of the Self reveals itself when the external crust of the sense of doership and enjoyership which is falsely imagined is completely erased out. The multiplicity and the duality of the universe should be denied in the light of the fact that the Lord, the one Self, alone exists. This omnipresent Self cannot be associated with individual functions, like doership and enjoyership. Name, form and action which characterise the world cannot be the natures of God, because these are objective perceptions and not eternal values. The universe, thus, gets renounced, because God is the only Truth. Tena tyaktena means "by such renunciation" consequent upon the knowledge of the only existence which is God. Renunciation is the result of the knowledge of Truth. Anything that is abandoned as unconnected with the Self does not become useful to the Self in any way. Everyone in the world is dependent on the not-Self. But when the not-Self is denied one cannot be dependent on it. The denial of the not-Self or the renunciation of the universe means that the Self is not helped by any external agency and it has to save itself through itself. It also means that previous to knowledge, i.e., when the Self appeared to be entangled in the not-self, it was in bondage, as it were, but now because of disentanglement it saves itself and protects itself and is dependent on itself. Because the Self is permanent its independence also is permanent. Bhunjeetbhah may also mean "enjoy", in which case the sense would be that through the renunciation of the not-Self there accrues to the Self the highest enjoyment, everything becomes its, and it experiences the Bliss of Liberation. It is a law that the greater the renunciation, the greater is the joy experienced because of the absence of desires. "Do not covet the wealth of anyone" means that, because God is the only reality, there is nothing worth coveting in this world. Because, "whose is wealth"? The wealth does not belong to anyone. All possessions are perishable. Therefore, there is no need of coveting anything. Only the knowledge that the Self is all, the Lord of all, should be acquired and everything else should be renounced. Everything is the atman and, hence, there is no value in desiring anything. As other than the atman nothing is, nothing can be desired or loved. Dhanam may also mean the dearest possession, which is one's own body. In this case the meaning would be: Do not covet any kind of body, not even a celestial body or even the body of the creator himself. Do not wish to be reborn in any kind of body, and aspire for liberation alone.