Skandapurana 16.225.16

16.225.16

.. yama uvāca .. ..
śṛṇu deva pravakṣyāmi yāvanto narakāḥ sthitāḥ ..
karmaṇā yena gaccheta mānavo dvijasattama ..
ekaviṃśatsamākhyātā narakā mama mandire .. 16 ..

Yama said: / "Listen, O noble one, I shall tell how many hells exist, / and by what deed a human would go [there], O best of brahmins. / Twenty-one hells are proclaimed in my abode.