Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 22
Sanskrit:
घृतं मे वीर भक्ष्यं स्यान्नेक्षे त्वान्यत्र मैथुनात् ।विवाससं तत् तथेति प्रतिपेदे महामना: ॥ २२ ॥
ITRANS:
ghṛtaṁ me vīra bhakṣyaṁ syānnekṣe tvānyatra maithunātvivāsasaṁ tat tathetipratipede mahāmanāḥ
Translation:
Urvaśī said: “My dear hero, only preparations made in ghee [clarified butter] will be my eatables, and I shall not want to see you naked at any time, except at the time of sexual intercourse.” The great-minded King Purūravā accepted these proposals.