Among the sons of Sagara Mahārāja was one named Asamañjasa, who was born from the King’s second wife, Keśinī. The son of Asamañjasa was known as Aṁśumān, and he was always engaged in working for the good of Sagara Mahārāja, his grandfather.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
यस्येरिता साङ्ख्यमयी दृढेह नौ- र्यया मुमुक्षुस्तरते दुरत्ययम् । भवार्णवं मृत्युपथं विपश्चितः परात्मभूतस्य कथं पृथङ्मतिः
yasyeritā sāṅkhyamayī dṛḍheha nau- ryayā mumukṣustarate duratyayam | bhavārṇavaṃ mṛtyupathaṃ vipaścitaḥ parātmabhūtasya kathaṃ pṛthaṅmatiḥ
SB 9.8.14