Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 20

Sanskrit:

कदाचिदथ गोविन्दो रामश्चाद्भ‍ुतविक्रम: ।विजह्रतुर्वने रात्र्यां मध्यगौ व्रजयोषिताम् ॥ २० ॥

ITRANS:

kadācid atha govindorāmaś cādbhuta-vikramaḥvijahratur vane rātryāṁmadhya-gau vraja-yoṣitām

Translation:

Once Lord Govinda and Lord Rāma, the performers of wonderful feats, were playing in the forest at night with the young girls of Vraja.

Purport:

This verse introduces a new pastime. According to the ācāryas, the occasion mentioned here is the Holikā-pūrṇimā, a day also known as Gaura-pūrṇimā.