प्राणो ब्रह्मेति व्यजानात् ।प्राणाद्ध्येव खल्विमानि भूतानि जायन्ते ।प्राणेन जातानि जीवन्ति ।प्राण' प्रयन्त्यभिसविशन्तीति ।तद्विज्ञाय ।पुनरेव वरुण पितरमुपससार ।अधीहि भगवो ब्रह्मेति ।तँ होवाच ।तपसा ब्रह्म विजिज्ञासस्व ।तपो ब्रह्मेति ।स तपोऽतप्यत ।स तपस्तप्त्वा ॥ १ ॥
In plain words
He understood that the vital breath, prana, is Brahman. For from prana alone indeed are all these beings born; once born, they live by prana; and into prana they dissolve and enter. Having realized this, he once again approached his father Varuna and said: 'Teach me, O revered one, about Brahman.' To him the father replied: 'Seek to know Brahman through austerity; austerity is Brahman.' He practiced austerity. And having performed that penance...
Close to the Sanskrit
He realized prana is Brahman. For from prana indeed verily these beings are born, by prana born they live, to prana they go forth and enter fully. Having known that, again indeed he approached Varuna the father: 'Teach, O venerable one, Brahman.' To him he spoke: 'Through austerity desire to know Brahman, austerity is Brahman.' He practiced austerity. Having performed austerity...