Mantra 6

अथ ह प्राणा अहंश्रेयसि व्यूदिरेऽहंश्रेयानस्म्यहं श्रेयानस्मीति ॥ ५.१.६ ॥

In plain words

Now the breaths disputed among themselves which was the better, each saying, "I am better, I am better."