Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 38

Sanskrit:

ऋषय ऊचु:इल्वलस्य सुतो घोरो बल्वलो नाम दानव: ।स दूषयति न: सत्रमेत्य पर्वणि पर्वणि ॥ ३८ ॥

ITRANS:

ṛṣaya ūcuḥilvalasya suto ghorobalvalo nāma dānavaḥsa dūṣayati naḥ satrametya parvaṇi parvaṇi

Translation:

The sages said: A fearsome demon named Balvala, the son of Ilvala, comes here every new-moon day and contaminates our sacrifice.

Purport:

First the sages tell Lord Balarāma the favor they would like Him to do for them.