Śatapatha Brāhmaṇa ("of a hundred paths") 7.5.1.18

7.5.1.18

etayorubhayorgṛhītayoḥ | asmādūrgudacikramiṣattāmetābhyāmubhābhyāmagṛhṇāttasmādetābhyāmubhābhyā mūr ggṛhītā yo hyevānnamatti sa prāṇiti tamūrjayati

Those two being kept back, strength wanted to go out of him. He kept it back by those two: hence strength is kept back by those two; for he who eats food, breathes; and to him it gives strength.