Bhagavad Gita Chapter 10.7
etāḿ vibhūtiḿ yogaḿ ca
mama yo vetti tattvataḥ
so ’vikalpena yogena
yujyate nātra saḿśayaḥ
Translation
One who is factually convinced of this opulence and mystic power of Mine engages in unalloyed devotional service; of this there is no doubt.