Garuda Mahā Purana - Achara Khaṇḍa
216 - Dharmashastra
Brahma said:
1. I Shall explain the characteristics of the Homa called Vaishvadeva. First repeat the mantra "Kravyadam Agnim,"2 etc after kindling the fire and performing Paryukshana (Sprinkling of water) Om, O Pavaka (fire god) Vaishvanara, here is a seat unto you sanctified by Aranigarbha.
2. Ibid., 10.16.9
O Maha Brahman! I am wakening up Vaishvanara. Then repeat the mantra "Om Vaishvanarena"3 etc.
3. AV. 7.108.2
2. Om Svaha to Prajapati. Om Svaha to Soma. Om Svaha to Bruhaspati, Om Svaha to Agni and Soma. Om Svaha to Indra and Agni. Om Svaha to Earth and Heaven. Om Svaha to Indra, Om Svaha to all Devas. Om Svaha to Brahman. Om Svaha to waters, to herbs and plants, to the planets, to the deities, to Indra, to Indra's officers, to Yama, to the officer of Yama, to all beings roaming the firmament, to Vasudha Pitrus. I offer oblation to those beings which, in their woe, roam in the mid-world and desire all round nourishment. May Pushtipati grant me nourishment. May he grant everything even to Chandalas and crows.
Summary of chapter 216 of the Garuda Mahā Purana - Achara Khaṇḍa is as follows:
The Divine Master defines specific metrical structures, Vṛtta, explaining syllable quantities, pauses, Yati, and poetic rhythms. As it happens, adhering to proper metrical rhythm invokes divine harmony during scriptural recitation.