At that time the great sage Nārada came to Kaṁsa. He was informed of Kaṁsa’s becoming compassionate to Vasudeva and returning his firstborn child. Nārada was very eager to accelerate the descent of Lord Kṛṣṇa as soon as possible. He therefore informed Kaṁsa that in Vṛndāvana personalities like Nanda Mahārāja and all the other cowherd men and their wives, and on the other side Vasudeva, his father Śūrasena and all his relatives born in the family of Vṛṣṇi of the Yadu dynasty, along with all their friends and well-wishers, were actually demigods. Nārada warned Kaṁsa to be careful of them, since Kaṁsa and his friends and advisors were all demons. Demons are always afraid of demigods. After being thus informed by Nārada about the appearance of the demigods in different families, Kaṁsa at once became very much alarmed. He understood that since the demigods had already appeared, Lord Viṣṇu must be coming soon. He at once arrested both his brother-in-law Vasudeva and Devakī and put them behind prison bars.
Within the prison, shackled in iron chains, Vasudeva and Devakī gave birth to a male child year after year, and Kaṁsa, thinking each of the babies to be the incarnation of Viṣṇu, killed them one after another. He was particularly afraid of the eighth child, but after the visit of Nārada, he came to the conclusion that any child might be Kṛṣṇa. Therefore it was better to kill all the babies who took birth from Devakī and Vasudeva.
This action of Kaṁsa is not very difficult to understand. There are many instances in the history of the world of persons in the royal order who have killed their father, brother or a whole family and friends for the satisfaction of their ambitions. There is nothing astonishing about this, for members of the demoniac, greedy royal order can kill anyone for their nefarious ambitions.
Kaṁsa was made aware of his previous birth by the grace of Nārada. He learned that in his previous birth he had been a demon of the name Kālanemi and that he had been killed by Viṣṇu. Having now taken his birth in the Bhoja family, he decided to become the deadly enemy of the Yadu dynasty; Kṛṣṇa was going to take birth in that family, and Kaṁsa was very much afraid that he would be killed by Kṛṣṇa, just as he had been killed in his last birth.
He first of all imprisoned his father, Ugrasena, because he was the chief king among the Yadu, Bhoja and Andhaka dynasties, and he also occupied the kingdom of Śūrasena, Vasudeva’s father. He declared himself the king of all such places.
Thus ends the Bhaktivedanta purport of the First Chapter of Kṛṣṇa, “The Advent of Lord Kṛṣṇa.”