ŚVETĀŚVATARA UPANISHAD · 6.15

एको हंसो भुवनस्यास्य मध्ये स एवाग्निः सलिले संनिविष्टः ।
तम् एव विदित्वाति मृत्युम् एति नान्यः पन्था विद्यते ऽयनाय ॥

eko haṃso bhuvanasyāsya madhye sa evāgniḥ salile saṃniviṣṭaḥ ।
tam eva viditvāti mṛtyum eti nānyaḥ panthā vidyate ’yanāya ॥

He is the one bird in the midst of the world; he is also (like) the fire (of the sun) that has set in the ocean. A man who knows him truly, passes over death; there is no other path to go.