Sad-dharma, or duty performed for going back to Godhead and thus becoming His unalloyed devotee, is the only pious activity; all others may pretend to be pious, but actually they are not. It is for this reason only that the Lord advises in the Bhagavad-gītā that one give up all so-called religious activities and completely engage in the devotional service of the Lord to become free from all anxieties due to the dangerous life of material existence.
-Shrimad Bhagavatam Canto 2 Chapter 10 Verse 4, Translation and Purport

यस्त्वात्मरतिरेव स्यादात्मतृप्त‍श्च मानवः ।
आत्मन्येव च सन्तुष्टस्तस्य कार्यं न विद्यते ॥ १७ ॥
But for one who takes pleasure in the Self, whose human life is one of self-realization, and who is satisfied in the Self only, fully satiated – for him there is no duty.
-Bhagavad-Gita Chapter 3 Verse 17