Skandapurana 5.25.41

5.25.41

tatra sa brāhmaṇo yāvadgaṃgātoyasamudbhavam ..
gaṃḍūṣaṃ kurute vaktre tāvacchuddho babhūva saḥ ..
udarādakhilaṃ toyaṃ niṣkrāṃtaṃ dvijasattamāḥ .. 41 ..

There, as soon as that brahmin took a mouthful / of the water from the Gaṅgā into his mouth, he became purified; / all the water [he had drunk] came out of his belly, O best of brahmins.