devakim vasudevam ca
vimucya prasrito ’bravit
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
After hearing the words of the goddess Durga, Kamsa was struck with wonder. Thus he approached his sister Devaki and brother-in-law Vasudeva, released them immediately from their shackles, and very humbly spoke as follows.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Kamsa was astonished because the goddess Durga had become the daughter of Devaki. Since Devaki was a human being, how could the goddess Durga become her daughter? This was one cause of his astonishment. Also, how is it that the eighth child of Devaki was a female? This also astonished him. Asuras are generally devotees of mother Durga, Sakti, or of demigods, especially Lord Siva. The appearance of Durga in her original eight-armed feature, holding various weapons, immediately changed Kamsa’s mind about Devaki’s being an ordinary human. Devaki must have had some transcendental qualities; otherwise why would the goddess Durga have taken birth from her womb? Under the circumstances, Kamsa, struck with wonder, wanted to compensate for his atrocities against his sister Devaki.