etam vibhutim yogam ca
mama yo vetti tattvatah
so’ vikalpena yogena
yujyate natra samsayah
(The Opulence of the Absolute, Text 07 Chapter 10)
Meaning: One who is factually convinced of this opulence and mystic power of Mine engages in unalloyed devotional service; of this there is no doubt.
Bhagavad Gita: Engage in unalloyed devotional service (The Opulence of the Absolute, Text 07 Chapter 10)