Being freed from attachment, fear and anger, being fully absorbed in Me and taking refuge in Me, many, many persons in the past became purified by knowledge of Meand thus they all attained transcendental love for Me. There are two ways of constantly thinking of Krsnaas a devotee and as an enemy. A devotee, of course, by his knowledge and tapasya, becomes free from fear and anger and becomes a pure devotee. Similarly, an enemy, although thinking of Krsna inimically, thinks of Him constantly and also becomes purified. This is confirmed elsewhere in Bhagavad-gita (9.30), where the Lord says:

Even if one commits the most abominable actions, if he engages in devotional service he is to be considered saintly because he is properly situated. A devotee undoubtedly worships the Lord with rapt attention. Similarly, if an enemy (suduracarah) always thinks of Krsna, he also becomes a purified devotee. The example given here concerns the grassworm that becomes beelike because of constantly thinking of the bee that forces it to enter a hole. By always thinking of the bee in fear, the grassworm starts to become a bee. This is a practical example. Lord Krsna appears within this material world for two purposesparitranaya sadhunam vinasaya ca duskrtam: [Bg. 4.8] to protect the devotees and annihilate the demons. The sadhus and devotees certainly think of the Lord always, but duskrtis, the demons like Kamsa and Sisupala, also think of Krsna in terms of killing Him. By thinking of Krsna, both the demons and devotees attain liberation from the clutches of material maya.