Śatapatha Brāhmaṇa ("of a hundred paths") 10.4.2.18

10.4.2.18

atha yaccaturviṃśatimātmano'kuruta tasmāccaturviṃśatyardhamāsaḥ saṃvatsaraḥ sa etaiścaturviṃśatyā triṃśadiṣṭakairātmabhirna vyabhavatsa pañcadaśāhno rūpāṇyapaśyadātmanastanvo muhūrtālokampṛṇāḥ pañcadaśaiva rātrestadyanmuhu trāyante tasmānmuhurtā atha yatkṣudrāḥ santa imāṃlokānāpūrayanti tasmāllokampṛṇāḥ

And because he made himself twenty-four bodies, therefore the year consists of twenty-four half-months. With these twenty-four bodies of thirty bricks each he had not developed (sufficiently). He saw the fifteen parts of the day, the muhûrtas, as forms for his body, as space-fillers (Lokamprinâs), as well as fifteen of the night; and inasmuch as they straightway (muhu) save (trai), they are (called) 'muhûrtâh'; and inasmuch as, whilst being small, they fill (pûr) these worlds (or spaces, 'loka') they are (called) 'lokamprinâh.'