Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 20
Sanskrit:
तत्र चक्रु: परिवृढौ गोपा रामजनार्दनौ ।कृष्णसङ्घट्टिन: केचिदासन् रामस्य चापरे ॥ २० ॥
ITRANS:
tatra cakruḥ parivṛḍhaugopā rāma-janārdanaukṛṣṇa-saṅghaṭṭinaḥ kecidāsan rāmasya cāpare
Translation:
The cowherd boys chose Kṛṣṇa and Balarāma as the leaders of the two parties. Some of the boys were on Kṛṣṇa’s side, and others joined Balarāma.