aprapya mam nivartante
(The Most Confidential Knowledge, Text 3, Chapter 9)
Meaning: Those who are not faithful in this devotional service cannot attain Me, O conqueror of enemies. Therefore they return to the path of birth and death in this material world.
Bhagavad Gita: Faithful in this devotional service (The Most Confidential Knowledge, Text 3, Chapter 9)