Srimad Bhagavatam Canto 08, Chapter 20, Text 12

SB 8.20.12

yadyapy asav adharmena
 mam badhniyad anagasam
tathapy enam na himsisye
 bhitam brahma-tanum ripum
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Although He is Visnu Himself, out of fear He has covered Himself in the form of a brahmana to come to me begging. Under the circumstances, because He has assumed the form of a brahmana, even if He irreligiously arrests me or even kills me, I shall not retaliate, although He is my enemy.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
If Lord Visnu as He is had come to Bali Maharaja and asked him to do something, Bali Maharaja certainly would not have refused His request. But to enjoy a little humor between Himself and His devotee, the Lord covered Himself as a brahmana-brahmacari and thus came to Bali Maharaja to beg for only three feet of land.

 

Srimad Bhagavatam Canto 08, Chapter 20, Text 11
Srimad Bhagavatam Canto 08, Chapter 20, Text 13