MUṆḌAKA UPANISHAD · 2.2.1

आविः संनिहितं गुहाचरं नाम
महत्पदमत्रैतत्समर्पितम् ।
एजत्प्राणन्निमिषच्च यदेतज्जानथ
सदसद्वरेण्यं परं विज्ञानाद्यद्वरिष्ठं प्रजानाम् ॥ १॥

āviḥ saṃnihitaṃ guhācaraṃ nāma
mahatpadamatraitatsamarpitam ।
ejatprāṇannimiṣacca yadetajjānatha
sadasadvareṇyaṃ paraṃ vijñānādyadvariṣṭhaṃ prajānām ॥ 1॥

Manifested, it is here set close within, moving in the secret heart, this is the mighty foundation and into it is consigned all that moves and breathes and sees. This that is that great foundation here, know, as the Is and Is-not, the supremely desirable, greatest and the Most High, beyond the knowledge of creatures.

Sri Aurobindo · CWSA 18, p. 139