Śrīmad-Bhāgavatam · Text 11.18.10
Who is speaking and story frame
यस्त्वेतत् कृच्छ्रतश्चीर्णं तपो नि:श्रेयसं महत् ।
कामायाल्पीयसे युञ्ज्याद् बालिश: कोऽपरस्तत: ॥ १० ॥
yas tv etat kṛcchrataś cīrṇaṁ
tapo niḥśreyasaṁ mahat
kāmāyālpīyase yuñjyād
bāliśaḥ ko ’paras tataḥ
One who with long endeavor executes this painful but exalted penance, which awards ultimate liberation, simply to achieve insignificant sense gratification must be considered the greatest fool.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.