In Pulaha-āśrama is the Gaṇḍakī River, which is the best of all rivers. The śālagrāma-śilā, the marble pebbles, purify all those places. On each and every marble pebble, up and down, circles like navels are visible.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
यत्राश्रमपदान्युभयतो नाभिभिर्दृषच्चक्रैश्चक्रनदी नाम सरित्प्रवरा सर्वतः पवित्रीकरोति
yatrāśramapadānyubhayato nābhibhirdṛṣaccakraiścakranadī nāma saritpravarā sarvataḥ pavitrīkaroti
SB 5.7.10