Skandapurana 6.3.72.24

6.3.72.24

ekaṃ muhūrtamātraṃ tu yāvatkṛṣṇaḥ sa dṛśyate .
kṣaṇamātreṇa caikena dāsī sā bhavate mama .. 72.24 ..

for just the span of a muhūrta, so long as he is seen as black.
And in just a single moment she will become my slave.