Bhashya
तं प्राणं क्षत्रमित्युपासीत ।प्राणो वै क्षत्रम्, प्रसिद्धम्एतत्- प्राणो हि वै क्षत्रम् ।कथं प्रसिद्धतेत्याह- त्रायतेपालयति एनं पिण्डं देहं प्राणः, क्षणितोः शस्त्रादिहिंसितात्पुनः मांसेन आपूरयति यस्मात्, तस्मात् क्षतत्राणात् प्रसि-द्धं क्षत्रत्वं प्राणस्य ।विद्वत्फलमाह-प्र क्षत्रमत्रम्, न त्रायतेअन्येन केनचिदित्यत्रम्, क्षत्रं प्राणः, तम् अत्रं क्षत्रं प्राणंप्राप्नोतीत्यर्थः ।शाखान्तरे वा पाठात् क्षत्रमात्रं प्राप्नोति,प्राणो भवतीत्यर्थः ।क्षत्रस्य सायुज्यं सलोकतां जयति, यएवं वेद ॥
In plain words
Meditate on that breath as ruling power. 'Breath truly is that power' — everyone already knows this; 'breath truly, verily, is that power.' Why is it so well known? Here is why: breath protects and nourishes this very lump of flesh, your body — whenever it is wounded, by a weapon or anything else, breath fills the wound back in with flesh. That healing of wounds is exactly why breath has earned the name of that ruling power. And here is the knower's reward: he reaches the highest form of that power, one that needs no protection from anything or anyone else — because that power simply is breath, and now he has become it. Some traditions read it more simply still: he attains that power, plain and unqualified — which just means he becomes breath. Either way, he wins full union and shared residence with that power, he who knows it this way.
Close to the Sanskrit
One should meditate upon that breath as ruling power. 'The breath, indeed, is ruling power' — this is well established; 'the breath, indeed, verily, is ruling power.' How is it well established? He says: the breath protects, guards this lump, this body; because, when it is wounded by a weapon and the like, it fills it again with flesh — therefore, from protecting the wound, the quality of ruling power in the breath is well established. He states the knower's fruit: 'he attains the foremost, unassailable ruling power' — unassailable means it needs no protection from anyone else at all; ruling power is the breath; he attains that unassailable ruling power, the breath — that is the meaning. Or, according to a reading in another recension, 'he attains mere ruling power', meaning he becomes the breath — that is the meaning. He wins union and co-residence with ruling power, he who thus knows.