Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 35: The History of Gaṅga
Text 1.35.21

या चान्याऽशैलदुहिता कन्यासीद्रघुनन्दन।
उग्रं सा व्रतमास्थाय तपस्तेपे तपोधना॥

cānyā śaila-duhitā kanyāsīd raghu-nandana
ugraṁ
vratam āsthāya tapas tepe tapo-dhanā

ca anyā = the other; śaila-duhitā = daughter of Himavān; kanyā = not yet married; asīt = was; raghu-nandana = O beloved child of the Raghu dynasty; ugram = a terrible; = she; vratam = vow; āsthāya = took up and; tapaḥ = austerity; tepe = performed; tapaḥ-dhanā = for austerity was her only wealth.

O beloved child of the Raghu dynasty, the other daughter of Himavān was not yet married. She took up a terrible vow and performed austerities, for austerity was her only wealth.

Incidentally, the sage also describes the history of Gaṅgā’s younger sister now.