Śatapatha Brāhmaṇa ("of a hundred paths") 6.1.2.16

6.1.2.16

so >syaiṣa citya āsīt | cetavyo hyasyāsīttasmāccityaścitya u evāyaṃ yajamānasya bhavati cetavyo hyasya bhavati tasmādveva cityaḥ

This, then, was his (Pragâpati's) 'kitya' (Agni to be set up on an altar-pile); for he had to be built up (ki) by him, and therefore was his 'kitya.' And so indeed he now is the Sacrificer's 'kitya;' for he is to be built up by him, and therefore is his 'kitya.'