SB 6.2.28

vṛddhāv anāthau pitarau
 nānya-bandhū tapasvinau
aho mayādhunā tyaktāv
 akṛtajñena nīcavat
Synonyms: 
vṛddhau — old; anāthau — who had no other person to look after their comforts; pitarau — my father and mother; na anya-bandhū — who had no other friend; tapasvinau — who underwent great difficulties; aho — alas; mayā — by me; adhunā — at that moment; tyaktau — were given up; akṛta-jñena — ungrateful; nīca-vat — like the most abominable low-class person.
Translation: 
My father and mother were old and had no other son or friend to look after them. Because I did not take care of them, they lived with great difficulty. Alas, like an abominable lower-class man, I ungratefully left them in that condition.
Purport: 

According to Vedic civilization, everyone has the responsibility for taking care of brāhmaṇas, old men, women, children and cows. This is the duty of everyone, especially an upper-class person. Because of his association with a prostitute, Ajāmila abandoned all his duties. Regretting this, Ajāmila now considered himself quite fallen.