The Lord is the seer, and the external energy, which is seen, works as both cause and effect in the cosmic manifestation. O greatly fortunate Vidura, this external energy is known as māyā or illusion, and through her agency only is the entire material manifestation made possible.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सा वा एतस्य सन्द्रष्टुः शक्तिः सदसदात्मिका । माया नाम महाभाग ययेदं निर्ममे विभुः
sā vā etasya sandraṣṭuḥ śaktiḥ sadasadātmikā | māyā nāma mahābhāga yayedaṃ nirmame vibhuḥ
SB 3.5.25