Śatapatha Brāhmaṇa ("of a hundred paths") 3.3.1.5

3.3.1.5

atha sphyamādāya parilikhati | vajro vai sphyo vajreṇaivaitatparilikhati triṣkṛtvaḥ parilikhati trivṛtaivaitadvajreṇa samantam parigṛhṇātyanatikramāya

Thereupon he takes the wooden sword and draws lines round (the foot-print): the wooden sword being a thunderbolt, it is with the thunderbolt that he draws round it. Thrice he draws round it, so that he encompasses it on all sides with a threefold thunderbolt, for no one to trespass upon it.