Agni, or heat, separated from His mouth, and all the directors of material affairs entered into it in their respective positions. By that energy the living entity expresses himself in words.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तस्याग्निरास्यं निर्भिन्नं लोकपालोऽविशत्पदम् । वाचा स्वांशेन वक्तव्यं ययासौ प्रतिपद्यते
tasyāgnirāsyaṃ nirbhinnaṃ lokapālo'viśatpadam | vācā svāṃśena vaktavyaṃ yayāsau pratipadyate
SB 3.6.12