Austerity (SB cantos 7 - 12)
Srimad-Bhagavatam
SB Canto 7
"O Lord, the intelligence of those who think themselves liberated but who have no devotion is impure. Even though they rise to the highest point of liberation by dint of severe penances and austerities, they are sure to fall down again into material existence, for they do not take shelter at Your lotus feet." The impersonalists cannot reach the Vaikuṇṭha planets to become associates of the Lord, and therefore, according to their desires, Kṛṣṇa gives them sāyujya-mukti. However, since sāyujya-mukti is partial mukti, they must fall again to this material world. When it is said that the individual soul falls from Brahmaloka, this applies to the impersonalist.