Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 17
Sanskrit:
कृष्णरामायिते द्वे तु गोपायन्त्यश्च काश्चन ।वत्सायतीं हन्ति चान्या तत्रैका तु बकायतीम् ॥ १७ ॥
ITRANS:
kṛṣṇa-rāmāyite dve tugopāyantyaś ca kāścanavatsāyatīṁ hanti cānyātatraikā tu bakāyatīm
Translation:
Two gopīs acted like Rāma and Kṛṣṇa in the midst of several others, who took the role of cowherd boys. One gopī enacted Kṛṣṇa’s killing of the demon Vatsāsura, represented by another gopī, and a pair of gopīs acted out the killing of Bakāsura.