Skanda Purana 16.187.7

16.187.7

mucyate pātakaiḥ sarvaiḥ śivalokaṃ sa gacchati ..
saptajanmakṛtaṃ pāpaṃ gaṃgāsāgarasaṃgame .. 7 ..

one is freed from all sins and goes to the world of Śiva. / The sin committed in seven births [is destroyed] at the confluence of the Gaṅgā and the ocean;