Skandapurana 1.3.25.69

1.3.25.69

tataḥ provāca bhagavānagniṃ prati maheśvaraḥ..
māsimāsi prataptānāṃ dehe tejo visṛjyatām.. 27.69 ..

Then the blessed Maheśvara said to Agni: / “Discharge that fiery splendour into the bodies of those [women] who are heated [by morning bathing] month after month.”