Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.4.19

2.1.4.19

taṃ vai tathaiva hareyuḥ | yathainameṣa pratyaṅṅupācaredeṣa vai yajño yadagniḥ pratyaṅ haivainaṃ yajñaḥ praviśati taṃ kṣipre yajña upanamatyatha yasmātparāṅ bhavati parāṅu haivāsmādyajño bhavati sa yo hainaṃ tatrānuvyāharetparāṅsmādyajño 'bhūditīśvaro ha yattathaiva syāt

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