Skandapurana 5.211.11

5.211.11

yaḥ saptamyāṃ sūryavāre snātvā tasya hṛde śubhe ..
māghamāse site pakṣe namasyati divākaram ..
sa kuṣṭhairmucyate sarvaistathā pāpairdvijo ttamāḥ .. 11 ..

Whoever, having bathed in his auspicious pool on a Sunday that is a seventh lunar day / in the bright fortnight of the month of Māgha, bows to the Sun, / is freed from all leprosy as well as sins, O best of brahmins.