Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 41

Sanskrit:

विप्रं कृतागसमपि नैव द्रुह्यत मामका: ।घ्नन्तं बहु शपन्तं वा नमस्कुरुत नित्यश: ॥ ४१ ॥

ITRANS:

vipraṁ kṛtāgasam apinaiva druhyata māmakāḥghnantaṁ bahu śapantaṁ vānamas-kuruta nityaśaḥ

Translation:

My dear followers, never treat a learned brāhmaṇa harshly, even if he has sinned. Even if he attacks you physically or repeatedly curses you, always continue to offer him obeisances.

Purport:

Lord Kṛṣṇa offers this instruction not only to His personal associates but to all those who claim to be followers of the Supreme Personality of Godhead.