Śatapatha Brāhmaṇa ("of a hundred paths") 8.7.3.3

8.7.3.3

na svayamātṛṇāyāmāvapedityu haika āhuḥ | prāṇaḥ svayamātṛṇā netprāṇānapidadhānīti sa vā aiva vapedannena vai prāṇā viṣṭabdhā yo vā annaṃ nātti saṃ vai tasya prāṇā rohanti tadyasya ha tathā kurvanti yathā śuṣkā sūrmī suṣiraivaṃ ha so 'muṣmiṃloke sambhavati tasmātsvayamātṛṇāyāmaiva vapet

'Let him not strew it on (the place of) the naturally-perforated one,' say some, 'lest he should stop up (the channels of) the vital airs, for the naturally-perforated one is the vital air.' Let him, nevertheless, strew it, for the vital airs are sustained by food, and whoever eats no food his (channels of the) vital airs grow up (and close): hence he for whom they act thus, comes to exist in yonder world even like a dry, hollow tube. Let him, therefore, by all means strew (loose soil) on (the place of) the naturally-perforated one.