Skandapurana 6.3.57.12

6.3.57.12

tatparva kīrtayāṃścakruḥ padmakaṃ nāma nāmataḥ .
ādityasya dinaṃ tvadya tithiḥ pañcadaśī tathā .. 57.12 ..

proclaimed that festival, namely by the name of Padmaka: / “Today is the day of the Sun (Sunday) and also the fifteenth lunar day;