Śatapatha Brāhmaṇa ("of a hundred paths") 7.4.2.1

7.4.2.1

svayamātṛṇāmupadadhāti | iyaṃ vai svayamātṛṇemāmevaitadupadadhāti tāmanantarhitām puruṣādupadadhātyannaṃ vai svayamātṛṇeyaṃ vai svayamātṛṇeyamu vā annamasyāṃ hi sarvamannam pacyate 'nantarhitamevāsmādetadanna dadhātyuttarāmuttaramevāsmādetadannaṃ dadhāti

He puts a Svayam-âtrinnâ (naturally-perforated brick) on (the gold man);--the (first) naturally-perforated one being this earth, he thus puts this earth thereon. He puts it on so as not to be separate from the man; for the naturally-perforated one means food, and the naturally-perforated one means this earth, and this earth is food, since it is on her that all food ripens: he thus places food close to him (the man, Agni). Upon (the man he puts it): he thus places the food upon him.