Adbhutasagara 48.83

48.83

saptamīmiti saptamīṃ niśām|
ādityapurāṇe|
savāyugātraṃ tvatha kṛṣṇaraktaṃ tvākasmikaṃ svaṃ ca purāgrasaṃstham|
narākṛtiṃ vīkṣya tribhistu varṣaiḥ sotkaṇṭhito yāti tanuṃ vihāya||

"The seventh" means the seventh night.
In the Ādityapurāṇa:
"Having seen an unexpected human form with an airy body, black and red, standing before his town [or himself],
he departs, leaving behind his body, longing, within three years."