Skandapurana 16.29.3

16.29.3

dhanvaṃtaraśate proktaṃ someśājjalamadhyagam..
kuṇḍaṃ pāpaharaṃ proktaṃ śatahastapramāṇataḥ ..
tatra snānaṃ prakurvīta vigāhya nidhimaṃbhasām .. 3 ..

At a distance of a hundred bows from Someśa, situated within the water, / is the pool destroying sin, declared to be a hundred cubits in measure; / having plunged into the storehouse of waters, one should perform ritual ablution there,