Chapter 15 · The Supreme Person · Krishna said
Bhagavad Gita 15.14 — The fire of digestion
अहं वैश्वानरो भूत्वा प्राणिनां देहमाश्रितः। प्राणापानसमायुक्तः पचाम्यन्नं चतुर्विधम् ॥
ahaṃ vaiśvānaro bhūtvā prāṇināṃ dehamāśritaḥ | prāṇāpānasamāyuktaḥ pacāmyannaṃ caturvidham ||
Meaning
Becoming the digestive fire (Vaishvanara) in the bodies of living beings, and joined with the incoming and outgoing breath, I digest the four kinds of food.