Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 6


अहो अस्मदभूद् भूरि पित्रोर्वृजिनमार्ययो: ।यद्धेतो: पुत्रमरणं यद्धेतोर्बन्धनं तयो: ॥ ६ ॥


aho asmad abhūd bhūripitror vṛjinam āryayoḥyad-dhetoḥ putra-maraṇaṁyad-dhetor bandhanaṁ tayoḥ


Just see how much suffering I have caused My offenseless parents! Because of Me their sons were killed and they themselves imprisoned.


Because Kaṁsa had heard a prophecy that the eighth son of Devakī would kill him, he tried to kill all her children. For the same reason, he imprisoned her and her husband, Vasudeva.