Louis IX of France quotes:

In order to avoid contention, never contradict anyone, except in case of sin or some danger to a neighbor; and when necessary to contradict others, and to oppose your opinion to theirs, do it with so much mildness and tact, as not to appear to do violence to their mind, for nothing is ever gained by taking up things with excessive warmth and hastiness.

In prosperity, give thanks to God with humility and fear lest by pride you abuse God's benefits and so offend him.