Lord Viṣṇu replied: Brahmā, Lord Śiva and I are the supreme cause of the material manifestation. I am the Supersoul, the self-sufficient witness. But impersonally there is no difference between Brahmā, Lord Śiva and Me.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
श्रीभगवानुवाच । अहं ब्रह्मा च शर्वश्च जगतः कारणं परम् । आत्मेश्वर उपद्रष्टा स्वयन्दृगविशेषणः
śrībhagavānuvāca | ahaṃ brahmā ca śarvaśca jagataḥ kāraṇaṃ param | ātmeśvara upadraṣṭā svayandṛgaviśeṣaṇaḥ
SB 4.7.50