Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 4
आज्ञायास्यै सपत्नीभिर्गरो दत्तोऽन्धसा सह ।सह तेनैव सञ्जात: सगराख्यो महायशा: ।सगरश्चक्रवर्त्यासीत् सागरो यत्सुतै: कृत: ॥ ४ ॥
ājñāyāsyai sapatnībhirgaro datto ’ndhasā sahasaha tenaiva sañjātaḥsagarākhyo mahā-yaśāḥsagaraś cakravarty āsītsāgaro yat-sutaiḥ kṛtaḥ
Knowing that she was pregnant, the co-wives of the wife of Bāhuka conspired to give her poison with her food, but it did not act. Instead, the son was born along with the poison. Therefore he became famous as Sagara [“one who is born with poison”]. Sagara later became the emperor. The place known as Gaṅgāsāgara was excavated by his sons.