Srimad Bhagavatam Canto 10, Chapter 69, Text 38

SB 10.69.38

vidama yoga-mayas te
 durdarsa api mayinam
yogesvaratman nirbhata
 bhavat-pada-nisevaya
 
Translation: 
 
[Narada said:] Now we understand Your mystic potencies, which are difficult to comprehend, even for great mystics, O Supreme Soul, master of all mystic power. Only by serving Your feet have I been able to perceive Your powers.
 
Purport: 
 
According to the acaryas, this verse indicates that even great mystics like Lord Brahma and Lord Siva cannot fully comprehend the mystic power of the Supreme Lord.
Srimad Bhagavatam Canto 10, Chapter 69, Text 37
Srimad Bhagavatam Canto 10, Chapter 69, Text 39