Śatapatha Brāhmaṇa ("of a hundred paths") 11.6.1.8

11.6.1.8

sa hovāca yānvai tatprācyāṃ diśyadrākṣīḥ puruṣaiḥ pu ruṣānparvāṇyeṣām parvaśaḥ saṃvraścam parvaśo vibhajamānānidaṃ tavedam mameti vanaspatayo vai te abhūvantsa yadvanaspatīnāṃ samidhamādadhāti tena vanaspatīnavarunddhe tena vanaspatīnāṃ lokaṃ jayati

He spake, ‘As to those men whom thou sawest in the eastern region being dismembered by men hewing off their limbs one by one, and saying, "This to thee, this to me!" they were the trees: when one puts fire-wood from trees on (the fire) he subdues the trees, and conquers the world of trees.