O Nārada [the Lord spoke], I regret that during this lifetime you will not be able to see Me anymore. Those who are incomplete in service and who are not completely free from all material taints can hardly see Me.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
एवं यतन्तं विजने मामाहागोचरो गिराम् । गम्भीरश्लक्ष्णया वाचा शुचः प्रशमयन्निव
evaṃ yatantaṃ vijane māmāhāgocaro girām | gambhīraślakṣṇayā vācā śucaḥ praśamayanniva
SB 1.6.21