Śatapatha Brāhmaṇa ("of a hundred paths") 3.4.1.20

3.4.1.20

so 'dhimanthanaṃ śakalamādatte | agnerjanitramasītyatra hyagnirjāyate tasmādāhāgnerjanitramasīti 3.4.1.[21]atha darbhataruṇake nidadhāti | vṛṣaṇau stha iti tadyāvevemau striyai sākaṃjāvetāvevaitau

He takes the bottom piece of wood, with the text (Vâg. S. V, 2), 'Thou art the birth-place of Agni;' for it is thereon that Agni is produced: hence he says, 'Thou art the birth-place of Agni.'