Skanda Purana 7.20.250

7.20.250

vyāsajijñāsayā bhastrāpadakṣetrasamākhyānāya gaṅgāvataraṇamupākhyātuṃ sagaropākhyānam sagaranāmasamākhyā, sagarasyā- śvamedhena yajanam, aśvāpaharaṇam, aśvānveṣaṇāya sāgarotkhananam, kapilāvamānanāt sagarasutānāṃ saṃhāraḥ, sagarā- jñayāṃśumataḥ kapilāśramagamanam .

Through the inquiry of Vyāsa, for the purpose of narrating the descent of the Gaṅgā in order to explain the Bhastrāpada sacred field, the subsidiary narrative of Sagara; the etymological account of the name Sagara; Sagara's sacrificing with a horse sacrifice; the theft of the horse; the digging up of the ocean to search for the horse; the slaughter of the sons of Sagara due to their disrespect toward Kapila; the departure of Aṃśumat to Kapila's hermitage at the command of Sagara.