The great oneness mentioned here, I believe, is both oneness within and oneness among - within individuals and among different creatures. In unity there is great strength, and virtue is the path to unity. He will not be wounded in battle. Tigers no place to use their claws, And weapons no place to pierce. Because he has no place for death to enter.
Unethical conduct provides many places for weapons to pierce.
Anyone who lives on the basis of any other than a virtuous mindset knows this. When we violate the deepest moral structures, we create enemies in our path and give hostages to fortune. Life and the power to live well depend on respecting the basic moral structure of reality in our words, deeds, and even thoughts. Sustainable success requires virtuous action. It is thus no optional add-on for a life of satisfactory achievement, but a basic ingredient and foundation for that to which we all properly aspire.