Tao te Ching: 50

Man comes into life and goes out to death.
Three out of ten are companions of life.
Three out of ten are companions of death.
And three out of ten in their lives lead from activity to death.
And for what reason?
Because of man's intensive striving after life.
I have heard that one who is a good preserver of life will
not meet tigers or wild buffalos.
And in fighting will not try to escape from weapons of war.
The wild buffalo cannot but its horns against him,
The tiger cannot fasten its claws in him,
And weapons of war cannot thrust their blades into him.
And for what reason?
Because in him there is no room for death.

Han Fei Tzu had an interesting thought about this, not so much that the translation was three of ten but three and ten. Thirteen, which is the number of the four limbs and the nine external cavities. There is more about that in Han Fei Tzu's work.

If it's three of ten, then Lao Tzu seems to be missing one in there somewhere. Perhaps that one is the one he is speaking of: the good preserver of life.

This seems to be rooted in the same segments as the non-violence protocols of the Buddhists. Do not harm, do what is best for life and life will do what you need. I'm somewhat baffled by this passage though, as many of the chapters are very practical advice that is easy to follow. The message of this one seems to be that your life will be more peaceful if you yourself are a good steward and preserver of life. Perhaps that is true. After all, in Chapter 46 he says that those who make war are plagued by war, and those who make peace live in peace.