Śatapatha Brāhmaṇa ("of a hundred paths") 3.5.4.3

3.5.4.3

tadvai devā aspṛṇvata | ta etaiḥ kṛtyā valagānudakhananyadā vai kṛtyāmutkhanantyatha sālasā moghā bhavati tatho evaiṣa etadyadyasmā atra kaściddviṣanbhrātṛvyaḥ kṛtyāṃ valagānnikhanati tānevaitadutkirati tasmāduparavān khanati sa dakṣiṇasya havirdhānasyādho 'dhaḥ praugaṃ khanati

The gods then prevailed. By means of these (sounding-holes) they dug up those magic charms. Now, when a charm is dug up, it becomes inoperative and useless. And in like manner, if any malicious enemy buries here charms by way of witchcraft for this (sacrificer), does he thereby dig them up; this is why he digs sounding-holes. He digs just beneath the fore-part of the shafts of the southern cart.