The works of Ādi Śaṅkarācārya

Viṣṇusahasranāmastotram

Verse 70

एको वशी सर्वभूतान्तरात्माएकं रूपं बहुधा यः करोति ।तमात्मस्थं येऽनुपश्यन्ति धीरा-स्तेषां सुखं शाश्वतं नेतरेषाम् ॥

In plain words

The sole ruler and inner self of all beings, who multiplies his single form into the many — those wise souls who realize him residing within their own hearts attain eternal joy, and no one else.

Close to the Sanskrit

The one controller, the inner self of all beings, who makes the one form manifold — those steady ones who perceive Him situated within the self, theirs is eternal happiness, not of others.