Verse 5.19.1

तद्यद्भक्तं प्रथममागच्छेत्तद्धोमीयं स यां प्रथमामाहुतिं जुहुयात्तां जुहुयात्प्राणाय स्वाहेति प्राणस्तृप्यति ॥ ५.१९.१ ॥

tadyadbhaktaṃ prathamamāgacchettaddhomīyaṃ sa yāṃ prathamāmāhutiṃ juhuyāttāṃ juhuyātprāṇāya svāheti prāṇastṛpyati || 5.19.1 ||

1. The first part of the food is like the first oblation. One who eats should offer it as an oblation to prāṇa, saying, ‘Prāṇāya svāhā’ [i.e., I offer this as an oblation to prāṇa]. With this, your prāṇa becomes pleased.

Word-for-word explanation:

Tat, therefore; yat bhaktam, that food which; prathamam āgacchet, comes first; tat, that; homīyam, is meant as an oblation; saḥ, he [who eats]; yām prathamām āhutim, that first oblation; juhuyāt, offers; tām, that; juhuyāt, offers; prāṇāya svāhā iti, [with the mantra] ‘Prāṇāya svāhā’; prāṇaḥ tṛpyati, [then] prāṇa is pleased.

Commentary:

Here eating is being compared to performing a sacrifice. Every time you put food into your mouth, it is as if you are offering an oblation. Prāṇa is the deity to whom you offer the first oblation. The word prāṇa in this context means that aspect of the vital force which is responsible for respiration.