Mudgalapurana 4.2.9

4.2.9

kṛṣṇā caturthī proktā yā tasyāḥ kṛṣṇāḥ prakīrtitāḥ |
tithayoḥ daśapañcākhyā jñātavyā vibudhaiḥ kila ||

The fifteen lunar days called dark are proclaimed to have arisen
from her who is called the dark Caturthī, as should be known by the wise.