Bhashya
तदेतत् मनआरुष्य चतुष्पाद्ब्रह्म, चत्वार पादा अस्येति ।कथं चतुष्पात्त्वं मनसा ब्रह्मण इति, आह-वाक्प्राणश्चक्षुश्रोत्रमित्येते पादा इत्यध्यात्मम् ।अथाधिदैवतम् आकाशस्यब्रह्मणोऽग्निर्वायुरादित्यो दिश इत्येते ।एवमुभयमेव चतुष्पा-द्ब्रह्म आदिष्टं भवति अध्यात्मं चैवाधिदैवतं च ।तत्र वागेवमनसो ब्रह्मणश्चतुर्थ पाद् इतरपादत्रयापेक्षया- वाचा हिपादेनेव गवादि वक्तव्यविषयं प्रति तिष्ठति, अतो मनसपाद इव वाक् ।तथा प्राणो घ्राणं पाद् , तेनापि गन्ध-विषयं प्रति च क्रामति ।तथा चक्षु पाद् श्रोत्रं पाद् इत्ये-वमध्यात्मं चतुष्पात्त्वं मनसो ब्रह्मण ।अथाधिदैवतम् अग्नि-र्वाग्वादित्यदिश आकाशस्य ब्रह्मण उदर इव गो पादा इवलग्ना उपलभ्यन्ते, तेन तस्य आकाशस्य अग्न्यादय पादाउच्यन्ते ।एवमुभयमध्यात्मं चैवाधिदैवतं च चतुष्पादादिष्टंभवति ॥
In plain words
Treating the mind as its foundation, Brahman is declared to be four-footed, having four distinct quarters. How is this four-footed nature understood? In relation to the individual, speech, breath, eye, and ear are its four quarters. In relation to the cosmos, fire, wind, sun, and the directions are those quarters. Thus, the four-footed Brahman is taught in both dimensions—the subjective and the cosmic. Among these, speech serves as the fourth quarter of the mental Brahman when compared to the other three; for just as an animal stands firmly on its foot to reach its destination, speech rests upon the object of expression. Thus, speech acts as a foot of the mind. Similarly, breath paired with the nose is a foot, reaching out toward the realm of scent. The eye and the ear are likewise quarters. Thus is the four-footedness of mental Brahman explained within the individual. In the cosmic sphere, fire, speech, the sun, and the directions are perceived as attached to the expanse of space—which is Brahman—much like the legs attached to the body of a cow. Therefore, fire and the other deities are designated as the feet of that space. Thus, the four-footed Brahman is fully revealed in both the inner and outer domains.
Close to the Sanskrit
That this Brahman having the mind as its base is four-footed, four are its feet, thus. How is the four-footedness of Brahman through the mind, it says—speech, prāṇa, eye, and ear, these are the feet, thus regarding the self. Now regarding the divinities, fire, wind, sun, and the directions, these. Thus both indeed are instructed as four-footed Brahman, the subjective and the cosmic. There speech alone is the fourth foot of mental Brahman in relation to the other three feet—for by speech, like by a foot, it stands towards the object to be spoken about, hence speech is like a foot of the mind. Likewise prāṇa is the nose as a foot, by that also it steps towards the object of smell. Likewise the eye is a foot, the ear is a foot, thus four-footedness of mental Brahman regarding the self. Now regarding the divinities, fire, speech, sun, and directions appear attached to cosmic Brahman like the belly or cow feet, therefore the fire and others are called the feet of that space. Thus both regarding the self and regarding the divinities are instructed as four-footed.