Srimad-Bhagavatam: Canto 4 - Chapter 1 - Verse 31
Sanskrit:
मुनय: पदवीं यस्य नि:सङ्गेनोरुजन्मभि: ।न विदुर्मृगयन्तोऽपि तीव्रयोगसमाधिना ॥ ३१ ॥
ITRANS:
munayaḥ padavīṁ yasyaniḥsaṅgenoru-janmabhiḥna vidur mṛgayanto ’pitīvra-yoga-samādhinā
Translation:
Nārada Muni continued: After trying this process for many, many births and remaining unattached to material contamination, placing themselves continually in trance and executing many types of austerities, many mystic yogīs were unable to find the end of the path of God realization.