Paramahamsa Upanishad, also known as Paramahamsa Parivrajaka Upanishad, is one of the Upanishads in Yajur Veda. Here you can download the PDF version of this Upanishad.
In this Upanishad, the conversation between Sage Narada and Lord Brahma about the characteristics of a Paramahamsa Parivrajaka is explained. When Narada asked the Lord about this, he replied “Paramahamsa would not wear any holy thread or clothes; he is the class of wisdom and the world of knowledge. He doesn’t speaks about himself but he acts universally.
As per the Lord Brahma, a Paramahamsa thinks “I myself am He, I am That which is ever calm, immutable, undivided, of the essence of knowledge-bliss, That alone is my real nature.”