Śatapatha Brāhmaṇa ("of a hundred paths") 2.4.1.12

2.4.1.12

atha pra vā vrajati pra vā dhāvayati | sa yatra velo manyate tatsyanttvā vācaṃ visṛjate 'tha proṣya parekṣya yatra velām manyate tadvācaṃ yacati sa yadyapi rājāntareṇa syānnaiva tamupeyāt

Thereupon he walks or drives off; and having got as far as what he considers the boundary line, he releases his speech. And when he returns from the journey, he maintains silence from the moment he sees what he considers to be the boundary. And even though there be a king inside (one's house), one must not go to him.