MUṆḌAKA UPANISHAD · 3.1.2

समाने वृक्षे पुरुषो निमग्नोऽनीशया शोचति मुह्यमानः ।
जुष्टं यदा पश्यत्यन्यमीशमस्य महिमानमिति वीतशोकः ॥ २॥

samāne vṛkṣe puruṣo nimagno’nīśayā śocati muhyamānaḥ ।
juṣṭaṃ yadā paśyatyanyamīśamasya mahimānamiti vītaśokaḥ ॥ 2॥

The soul is the bird that sits immersed on the one common tree; but because he is not lord he is bewildered and has sorrow. But when he sees that other who is the Lord and beloved, he knows that all is His greatness and his sorrow passes away from him.