Mahabharata — Vana Parva, Shloka 17
युधिष्ठिरस्य अर्जुनप्रेषण-युक्तिवर्णनम् | Yudhiṣṭhira’s Rationale for Sending Arjuna and Request to Dhaumya
त्रिरात्रमुषित: शाकं भक्षयित्वा नर: शुचि: । शाकाहारस्य यत् किंचिद् वर्षद्वादिशभि: कृतम्
trirātram uṣitaḥ śākaṃ bhakṣayitvā naraḥ śuciḥ | śākāhārasya yat kiñcid varṣadvādaśibhiḥ kṛtam
古拉斯底耶说道：“若有人保持清净，住持三夜，只以菜叶为食，便能获得那种仅食青蔬之戒行修持十二年所生的一切功德。”
घुलस्त्य उवाच
Educational Q&A
The verse teaches that disciplined restraint in diet, combined with purity, can yield great spiritual merit; even a short, sincere observance may equal the fruit of a much longer practice.
Ghūlastya is describing the fruit (phala) of an austerity: staying for three nights while eating only greens, asserting that this brief observance grants the same merit attributed to maintaining a greens-only regimen for twelve years.