Shankara's explanation of the Brahman.

 

Who is the Brahman?

The fool thinks, "I am the body"; the intelligent man thinks, "I am an individual soul united with the body." But the wise man, in the greatness of his knowledge and spiritual discrimination, sees the Self as the only reality and thinks, "I am Brahman." 

Source:

https://www.onelittleangel.com/wisdom/quotes/saint.asp?mc=60