योऽप्सु तिष्ठन्नद्भ्योऽन्तरो यमापो न विदुर्यस्यापः शरीरं योऽपोऽन्तरो यमयत्येष त आत्मान्तर्याम्यमृतः ॥३,७.४ ॥
In plain words
He who dwells in the waters, yet is within the waters, whom the waters do not know, whose body the waters are, who from within controls the waters — he is thy Self, the inner controller, the immortal.