Śatapatha Brāhmaṇa ("of a hundred paths") 7.3.1.21

7.3.1.21

atha dakṣiṇataḥ | abhyāvartasva pṛthivi yajñena payasā saheti yathaiva yajustathā bandhurvapāṃ te agniriṣito arohaditi yadvai kiṃ cāsyāṃ sāsyai vapā tāmagniriṣita upādīpto rohati tāmāhṛtyāntareṇa pakṣasaṃdhimātmannupadadhāti sa yo dakṣiṇāyāṃ diśi raso 'tyakṣarattamasminnetaddadhātyatho dakṣiṇāmevāsminnetaddiśaṃ dadhāti

Then (he fetches a clod) from the south, with (Vâg. S. XII, 103), 'Turn hither, O Earth, with sacrifice, with milk!' as the text, so the meaning;--'Agni, sent forth, hath mounted thy skin;' whatsoever is on this (earth) that is her skin; and that (skin) Agni mounts, when sent forth, when blazing forth. Having brought it he puts it on the body (of the altar) inside the junction of the (right) wing (and the body): he thereby puts into him (Agni) what vital sap had flowed from him in the southern direction, and also the southern region itself he bestows upon him.