Śatapatha Brāhmaṇa ("of a hundred paths") 6.3.3.25

6.3.3.25

pari vājapatiḥ kaviḥ | pari tvāgne puraṃ vayaṃ tvamagne dyubhirityagnimevāsmā etadupastutya varma karoti parivatībhiḥ parīva hi pura āgneyībhiragnipurāmevāsmā etatkaroti sā haiṣāgnipurā dīpyamānā tiṣṭhati tisṛbhistripuramevāsmā etatkaroti tasmādu haitatpurām paramaṃ rūpaṃ yattripuraṃ savai varṣīyasā-varṣīyasā candasā parām-parāṃ lekhāṃ varīyasīṃ karoti tasmātpurām parā-parā varīyasī lekhā bhavanti lekhā hi puraḥ

[Vâg. S. XI, 25-27] 'Around the wise lord of strength--,' 'Around (us) we (place) thee, O Agni, as a rampart--,' 'With the days, thou Agni--,' in thus praising Agni he makes a fence for him by means of (verses) containing the word 'pari' (around), for all round, as it were, (run) the ramparts;--(he does so by verses) relating to Agni: a stronghold of fire he thus makes for him, and this stronghold of fire keeps blazing;--(he does so) by three (verses): a threefold stronghold he thus makes for him; and hence that threefold stronghold is the highest form of strongholds. Each following (circular) line he makes wider, and with a larger metre: hence each following line of strongholds is wider, for strongholds (ramparts) are lines.