Shatapatha Brahmana 10.1.1.3

10.1.1.3

sa yaḥ sa saṃvatsaraḥ prajāpatirvyasraṃsata ayameva sa yo'yamagniścīyate'tha yānyasya tānyahorātrāṇi parvāṇi vyasraṃsanteṣṭakā eva tāstadyadetā upadadhāti yānyevāsya tānyahorātrāṇi parvāṇi vyasraṃsanta tānyasminnetatpratidadhāti tadetadatraiva yajuścitamatrāptam

And that Pragâpati who became relaxed is this very Fire-altar which here is built; and those joints of his, the days and nights, which became relaxed are no other than the bricks;--thus, when he lays down these (in the layers of the altar), he thereby restores to him those joints of his, the days and nights, which had become relaxed: and thus it is even in this (building of the altar) that this Yagus is built up and secured (for Pragâpati).