Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.4.22

2.1.4.22

eṣa u vai prāṇaḥ | te vai tathaiva hareyuryathainameṣa pratyaṅṅupācaretpratyaṅ haivainam prāṇaḥ praviśatyatha yasmātparāṅ bhavati parāṅu haivāsmātprāṇo bhavati sa yo hainaṃ tatrānuvyāharetparāṅsmātprāṇo 'bhūditīśvaro ha yattathaiva syāttasmādu tathaiva hareyuḥ

And, verily, that (fire) is the (sacrificer's) breath. Let them, therefore, carry it in such wise that it turns towards him; for it is in the direction of him that the breath enters into him. And from whomsoever it (the fire) turns away; from him the breath also turns away; and if any one were to curse him, saying, 'May the breath turn away from him!' he would indeed be liable to fare thus.