Verse 10.4.4.4

sarvā evaitā iṣṭakāḥ sāhasrīrupāsīta rātrisahasreṇa rātrisahasreṇaikaikām pariśritaṃ sampannāmupāsītāhaḥsahasreṇāhaḥsahasreṇaikaikāmaharbhājamardhamāsasahasreṇārd hamāsasahasreṇaikaikāmardhamāsabhājam māsasahasreṇa-māsasahasreṇaikaikām māsabhājamṛtusahasreṇartṛsahasreṇaikaikāmṛtubhājam muhūrtasahasreṇa-muhūrtasahasreṇaikaikām muhūrtabhājaṃ saṃvatsarasahasreṇa saṃvatsaraṃ te ya etamevamagniṃ saṃvatsareṇa sampannaṃ viduḥ sahasratamīṃ hāsya te kalāṃ viduratha ya enamevaṃ na vidurna hāsya te sahasratamīṃ cana kalāṃ viduratha ya evaivaṃ veda yo vaitatkarma kurute sa haivaitaṃ sarvaṃ kṛtsnam prājāpatyamagnimāpnoti yam prajāpatirāpnottasmādevaṃvittapa eva tapyeta yadu ha vā evaṃvittapa tapyata ā maithunātsarvaṃ hāsya tatsvargaṃ lokamabhisambhavati

Preview of English translation:

4. Let him look upon all these bricks as a thousandfold: let him look upon each enclosing-stone as charged with a thousand nights, each day-holder with a thousand days, each half-moon-holder with a thousand half-moons, each month-holder with a thousand months, each season-holder with a thousand seasons, each muhurta-holder with a thousand muhurtas, and the year with a thousand years. They who thus know this Agni as being endowed with a thousand, know his one-thousandth digit; but they who do not thus know him, do not even know a one-thousandth digit of him. And he alone who so knows this, or who performs this sacred work, obtains this whole and complete Prajapatean Agni whom Prajapati obtained. Wherefore let him who knows this by all means practise austerities; for, indeed, when he who knows this practises austerities, even to (abstention from) sexual intercourse, every (part) of him will share in the world of heaven.

For a detailled translation, including proper diacritics and footnotes, go the full English translation.