Śatapatha Brāhmaṇa ("of a hundred paths") 6.4.1.5

6.4.1.5

sa vā abhryā khanan | vācā khanāmi khanāma ityāha vāgvā abhrirārambhāyaiveyaṃ vaiṇavī kriyate vācā vā etamabhryā devā akhanaṃstathaivainamayametadvācaivābhryā khanati

Now while digging with the spade, he says with speech 'I dig,' 'we dig,' for the spade is speech. It is for his undertaking that this bamboo (spade) is made; and with speech for a spade, the gods dug him up; and in like manner does this one now dig him up with speech for a spade (or, with the speech-spade).