BṚHADĀRAṆYAKA UPANISHAD · 1.5.23

अथैष श्लोको भवति --
यतश् चोदेति सूर्यो ऽस्तं यत्र च गच्छतीति ।
प्राणाद् वा एष उदेति प्राणे ऽस्तम् एति ।
तं देवाश् चक्रिरे धर्मं स एवाद्य स उ श्व इति ।
यद् वा एते ऽमुर्ह्य् अध्रियन्त तद् एवाप्य् अद्य कुर्वन्ति ।
तस्माद् एकम् एव व्रतं चरेत् प्राण्याच् चैवापान्याच् च ।
नेन् मा पाप्मा मृत्युर् आप्नवद् इति ।
यद्य् उ चरेत् समापिपयिषेत् तेनो एतस्यै देवतायै सायुज्यं सलोकतां जयति ॥

athaiṣa śloko bhavati --
yataś codeti sūryo ’staṃ yatra ca gacchatīti ।
prāṇād vā eṣa udeti prāṇe ’stam eti ।
taṃ devāś cakrire dharmaṃ sa evādya sa u śva iti ।
yad vā ete ’murhy adhriyanta tad evāpy adya kurvanti ।
tasmād ekam eva vrataṃ caret prāṇyāc caivāpānyāc ca ।
nen mā pāpmā mṛtyur āpnavad iti ।
yady u caret samāpipayiṣet teno etasyai devatāyai sāyujyaṃ salokatāṃ jayati ॥

And here there is this Sloka: 'He from whom the sun rises, and into whom it sets' (he verily rises from the breath, and sets in the breath) 'Him the Devas made the law, he only is to-day, and he to-morrow also' (whatever these Devas determined then, that they perform to-day also ). Therefore let a man perform one observance only, let him breathe up and let him breathe down, that the evil death may not reach him. And when he performs it, let him try to finish it. Then he obtains through it union and oneness with that deity (with prâna).

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)