Bhashya
अन्तर्यामीति-अत आह- यमन्तर्यामिणं पृथिवी देवतापिन वेद-मद्यन्यः कश्चिद्वर्तत इति ।यस्य पृथिवी शरीरम्-यस्य च पृथिव्येव शरीरम्, नान्यत्- पृथिवीदेवताया य-च्छरीरम्, तदेव शरीरं यस्य ; शरीरग्रहणं च उपलक्षणार्थम् ;करणं च पृथिव्याः तस्य ; स्वकर्मप्रयुक्तं हि कार्यं करणं चपृथिवीदेवतायाः ; तत् अस्य स्वकर्माभावात् अन्तर्यामिणोनित्यमुक्तत्वात्, परार्थकर्तव्यतास्वभावत्वात् परस्य यत्कार्यंकरणं च-तदेवास्य, न स्वतः ; तदाह- यस्य पृथिवी श-रीरमिति ।देवताकार्यकरणस्य ईश्वरसाक्षिमात्रसांनिध्येन हिनियमेन प्रवृत्तिनिवृत्ती स्याताम् ; य ईदृगीश्वरो नारायणा-ख्यः, पृथिवीं पृथिवीदेवताम्, यमयति नियमयति स्वव्या-पारे, अन्तरः अभ्यन्तरस्तिष्ठन्, एष त आत्मा, ते तव,मम च सर्वभूतानां च इत्युपलक्षणार्थमेतत्, अन्तर्यामी य-स्त्वया पृष्टः, अमृतः सर्वसंसारधर्मवर्जित इत्येतत् ॥
In plain words
'The inner controller' -- that is what he was asked about -- 'whom even the earth, as a deity, does not know' -- she goes on thinking someone other than herself exists at all. 'Whose body is the earth' means exactly this: the earth, and nothing else, is his body. Whatever belongs to the deity Earth as her body, that same thing is the body of the one being described here. Mentioning 'body' stands in for the whole picture -- the earth is also his instrument. Because her own effects and instruments, as a deity, are set in motion by her own past action. But he, the inner controller, has no action of his own driving him: he is eternally free, and his whole nature is to act only for another's sake, never his own. So whatever effect or instrument exists, it belongs to someone else, not to him. That is exactly why the text says, 'whose body is the earth'. It is only because the lord is present as a silent witness that the deity's own effects and instruments start and stop at all, and this happens of strict necessity. Such a lord -- called Narayana -- governs the earth, the deity Earth, in her proper function, standing inside her, within. He is your self -- and 'your' here really means yours, mine, and every being's; it stands for the whole. The inner controller you asked about is immortal, entirely free of everything that belongs to this changing world. That is the meaning.
Close to the Sanskrit
'...the inner controller whom' -- hence it is said -- 'the inner controller whom even the deity Earth does not know' -- thinking, 'someone other than me exists today'. 'Whose body is the earth' -- of whom the earth alone is the body, not anything else; whatever is the body of the deity Earth, that alone is the body of whom it is spoken. And the mention of 'body' is for the purpose of indication. And the earth is also his instrument. For the effect and instrument of the deity Earth are prompted by her own action. But for him, the inner controller, since he has no action of his own -- because of his eternal freedom, because his very nature is to act for the sake of another -- whatever is the effect and instrument, that belongs to another; it is not from himself. That is why it says: 'whose body is the earth'. For it is only through the mere presence of the lord as witness, of necessity, that the activity and cessation of activity of the deity's effect and instrument occur. Such a lord, named Narayana, governs, regulates, the earth, the deity Earth, in her own function, standing within, inside; he is your self -- 'your' meaning yours, and mine, and of all beings; this is for the purpose of indication; the inner controller about whom you asked is immortal, devoid of every property of transmigratory existence -- this is the meaning.