The works of Ādi Śaṅkarācārya

Viṣṇusahasranāmastotram

Verse 132

विस्तारः सर्वभूतस्य विष्णोः सर्वमिदं जगत् ।द्रष्टव्यमात्मवत्तस्मादभेदेन विचक्षणैः ॥

In plain words

This whole world is Viṣṇu spread wide — Viṣṇu who has become every single being. So the clear-sighted are to see it as the Self, with no difference drawn anywhere.

Close to the Sanskrit

This entire world is the expansion of Viṣṇu, who has become all beings; therefore it is to be seen as the Self, without difference, by the discerning.