योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-167, verse-44

किमत्र बाह्यं किं वान्तः किं दृश्यं कास्य दृश्यता ।
शिवं शान्तमशान्तं च सर्वमोमिति शाम्यताम् ॥ ४४ ॥

kimatra bāhyaṃ kiṃ vāntaḥ kiṃ dṛśyaṃ kāsya dṛśyatā ,
śivaṃ śāntamaśāntaṃ ca sarvamomiti śāmyatām 44

44. What is there the interior or exterior of it, and that what is visible and invisible in it; all this is in the Lord whether active or quiescent, know all to be the om or on and rest quiet.