Vishnupurana 2.6.36

2.6.36

yāvanto jantavaḥ svarge tāvanto narakaukasaḥ
pāpakṛd yāti narakaṃ prāyaścittaparāṅmukhaḥ //

The gods in heaven are beheld by the inhabitants of hell, as they move with their heads inverted; whilst the god, as they cast their eyes downwards, behold the sufferings of those in hell. The various stages of existence, Maitreya, are inanimate things, fish, birds, animals, men, holy men, gods, and liberated spirits; each in succession a thousand degrees superior to that which precedes it: and through these stages the beings that are either in heaven or in hell are destined to proceed, until final emancipation be obtained. That sinner goes to Naraka who neglects the due expiation of his guilt.