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 prana).

In plain words: A verse says the sun rises and sets in breath, and the gods made breath the lasting law. So a person should keep one practice: breathing in and breathing out, so death does not reach him. If he keeps it up to the end, he becomes one with breath, the life-force (prana).