Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.4.26

2.1.4.26

athedaṃ dvitīyam | tūṣṇīmevāgra upaspṛśatyathodyacati bhūrbhuvaḥ svarityeva dvitīyenādadhāti yo vā asyāmapratiṣṭhito bhāramudyacati nainaṃ śaknotyudyantuṃ saṃ hainaṃ śṛṇāti

Then there is this other. Silently he touches (the foot-print with it) in the first place; he then lifts it up, and at the second time lays it down with 'Earth! ether! heaven!' For he who wants to lift a load without having a firm footing on this (earth), cannot lift it; nay, it crushes him.