KAṬHA UPANISHAD · 2.1.12

अङ्गुष्ठमात्रः पुरुषो मध्य आत्मनि तिष्ठति ।
ईशानं भूतभव्यस्य न ततो विजुगुप्सते । एतद्वै तत् ॥ १२॥

aṅguṣṭhamātraḥ puruṣo madhya ātmani tiṣṭhati ।
īśānaṃ bhūtabhavyasya na tato vijugupsate । etadvai tat ॥ 12॥

The Purusha who is seated in the midst of ourself is no larger than the finger of a man. He is the lord of what was and what shall be; Him having seen one shrinketh not from aught nor abhorreth any. This is the thing thou seekest.