Bhashya
पृथिव्यै पृथिव्याः च एनम् अग्नेश्च दैवी अधिदैवात्मि-का वाक् एनं कृतसंप्रत्तिकम् आविशति; सर्वेषां हि वाचउपादानभूता दैवी वाक् पृथिव्यग्निलक्षणा; सा ह्याध्यात्मि-कासङ्गादिदोषैर्निरुद्धा ।विदुषस्तद्दोषापगमे आवरणभङ्गइवोदकं प्रदीपप्रकाशवच्च व्याप्नोति; तदेतदुच्यते-पृथि-व्या अग्नेश्चैनं दैवी वागाविशतीति ।सा च दैवी वाक् अ-नृतादिदोषरहिता शुद्धा, यया वाचा दैव्या यद्यदेव आत्म-ने परस्मै वा वदति तत्तत् भवति-अमोघा अप्रतिबद्धा अ-स्य वाग्भवतीत्यर्थः ॥
In plain words
The cosmic divine speech rooted in earth and fire enters the one who has brought his identification to completion. For this divine speech is the very substance of all words, though it is blocked by personal attachments and flaws. When a wise person clears away those obstacles—just as a veil is torn away, or as water and the clear light of a lamp fill a space—that speech pervades entirely. This is what is meant when it is said that the divine speech of earth and fire enters him. That divine speech is pure and free from falsehood: whatever such speech he utters for himself or for another, it comes to pass. His word becomes infallible, completely free of any obstruction.
Close to the Sanskrit
From earth and from fire, the divine speech associated with cosmic deities enters this one who has completed the identification; for the divine speech characterized by earth and fire is the material cause of all speech, but it is obstructed by defects such as attachments originating in personal limitations. Upon the removal of those defects for the wise person, like the breaking of a veil, water, and the light of a lamp, it pervades; this is what is said: 'Divine speech from earth and fire enters him.' And that divine speech is pure, free from defects such as falsehood; whatever speech divine he speaks either for himself or for another, that very thing becomes—meaning his speech becomes infallible and unobstructed.