Śatapatha Brāhmaṇa ("of a hundred paths") 7.5.1.13

7.5.1.13

te retaḥsicorvelayopadadhāti | pṛṣṭayo vai retaḥsicau madhyamu pṛṣṭayo madhyata evāsminnetadannaṃ dadhātyuttare uttaramevāsmādetadannaṃ dadhātyaratnimātre 'ratnimātrāddhyannamadyate

He puts them down at the distance of the two retahsik,--the retahsik being the ribs, and the ribs being the middle: he thus puts food into the middle of him (Agni);--on the north (upper) side (of the central brick): he thus puts the food upon him;--at the distance of a cubit, for from a cubit's distance food is (taken by the hand and) eaten.