SB 10.44.39

sa nityadodvigna-dhiyā tam īśvaraṁ
 pibann adan vā vicaran svapan śvasan
dadarśa cakrāyudham agrato yatas
 tad eva rūpaṁ duravāpam āpa
Synonyms: 
saḥ — he, Kaṁsa; nityadā — constantly; udvigna — anxious; dhiyā — with mind; tam — Him; īśvaram — the Supreme Lord; piban — while drinking; adan — eating; — or; vicaran — walking; svapan — sleeping; śvasan — breathing; dadarśa — saw; cakra — the disc weapon; āyudham — in His hand; agrataḥ — before himself; yataḥ — because; tat — that; eva — same; rūpam — personal form; duravāpam — very difficult to achieve; āpa — he achieved.
Translation: 
Kaṁsa 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 Kaṁsa achieved the rare boon of attaining a form like the Lord’s.
Purport: 

Although born out of fear, Kaṁsa’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.