Srimad Bhagavatam Canto 10, Chapter 44, Text 39

SB 10.44.39

sa nityadodvigna-dhiya tam isvaram
 pibann adan va vicaran svapan svasan
dadarsa cakrayudham agrato yatas
 tad eva rupam duravapam apa
 
Translation: 
 
Kamsa had always been disturbed by the thought that the Supreme Lord was to kill him. Therefore when drinking, eating, moving about, sleeping or simply breathing, the King had always seen the Lord before him with the disc weapon in His hand. Thus Kamsa achieved the rare boon of attaining a form like the Lord’s.
 
Purport: 
 
Although born out of fear, Kamsa’s constant meditation on the Supreme Lord eradicated all his offenses, and therefore the demon was liberated upon his death at the Lord’s hands.
Srimad Bhagavatam Canto 10, Chapter 44, Text 38
Srimad Bhagavatam Canto 10, Chapter 44, Text 40