Bhagavatapurana 5.22.9

5.22.9

_*
atha cāpūryamāṇābhiś ca kalābhir amarāṇāṃ kṣīyamāṇābhiś ca kalābhiḥ pit-ṇām aho-rātrāṇi pūrva-pakṣāpara-pakṣābhyāṃ vitanvānaḥ sarva-jīva-nivaha-prāṇo jīvaś caikam ekaṃ nakṣatraṃ triṃśatā muhūrtair bhuṅkte //

9. In the region of the celestials and the Pitris the moon makes days and nights respectively by means of his waxing and waning rays, which give rise to the bright and dark fortnights; the Moon is the life of all the living beings, hence also called 'Life';

and he occupies (is in conjunction with) each of the 28 constellations for 30 muhurthas (i. e., 24 hrs).