Advaita Teachings in the Bhagavad Purana

That from which creation and destruction are definitely known to emerge, is the resort which is called the Highest Brahman, the Highest Self.
Whatever is sat or asat is not different from Hari (Vishnu).
In the beginning, before the creation, I (Vishnu) alone was in existence. There was nothing else – neither sat or asat nor their cause. There was deep sleep everywhere. After the creation of the universe what exists, is I. I am the universe. What remains is me.
Brahma says “Bhagavan, after a very long time you have been realized by me today. It is indeed the defect of beings conditioned by body that your essential nature is not realized by them. Nothing other than you exists. Anything else is not pure because it is you who appear to be many due to the mixture of the qualities by your creative energy.