SB 3.6.12
tasyagnir asyam nirbhinnam
loka-palo ’visat padam
vaca svamsena vaktavyam
yayasau pratipadyate
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
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.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The mouth of the gigantic universal form of the Lord is the source of the speaking power. The director of the fire element is the controlling deity, or the adhidaiva. The speeches delivered are adhyatma, or bodily functions, and the subject matter of the speeches is material productions, or the adhibhuta principle.