Brihadaranyaka Upanishad 6.1

ॐ । यो ह वै ज्येष्ठं च श्रेष्ठं च वेद ज्येष्ठश्च ह वै श्रेष्ठश्च भवति; प्राणो वाव ज्येष्ठश्च श्रेष्ठश्च ॥

om. yo ha vai jyeshtham cha shreshtham cha veda jyeshthashcha ha vai shreshthashcha bhavati; praano vaava jyeshthashcha shreshthashcha

Om. He who knows the oldest and the greatest becomes himself the oldest and the greatest. The vital force (Prana) is indeed the oldest and the greatest.

ॐ। जो ज्येष्ठ और श्रेष्ठ को जानता है, वह स्वयं ही ज्येष्ठ और श्रेष्ठ हो जाता है। प्राण ही ज्येष्ठ और श्रेष्ठ है।