Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 4

Sanskrit:

ऊषु: सरस्वतीतीरे जलं प्राश्य यतव्रता: ।रजनीं तां महाभागा नन्दसुनन्दकादय: ॥ ४ ॥

ITRANS:

ūṣuḥ sarasvatī-tīrejalaṁ prāśya yata-vratāḥrajanīṁ tāṁ mahā-bhāgānanda-sunandakādayaḥ

Translation:

Nanda, Sunanda and the other greatly fortunate cowherds spent that night on the bank of the Sarasvatī, strictly observing their vows. They fasted, taking only water.

Purport:

Śrīla Viśvanātha Cakravartī explains that Sunanda is the younger brother of Nanda Mahārāja.