SB 10.64.41

vipraṁ kṛtāgasam api
 naiva druhyata māmakāḥ
ghnantaṁ bahu śapantaṁ vā
 namas-kuruta nityaśaḥ
Word for word: 
vipram — a learned brāhmaṇa; kṛta — having committed; āgasam — sin; api — even; na — not; eva — indeed; druhyata — do not treat inimically; māmakāḥ — O My followers; ghnantam — striking physically; bahu — repeatedly; śapantam — cursing; — or; namaḥ-kuruta — you should offer obeisances; nityaśaḥ — always.
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.