“Avoid contention and hostility when it only drives you to trouble, but never let others intimidate you just because you prefer peace and quiet.”
Related quotes

“Sometimes you best avoid talking by being quiet, but sometimes you best avoid talking by talking.”
Source: We Are All Completely Beside Ourselves

Source: The Prince (1513), Ch. 3 (as translated by RM Adams). Variants [these can seem to generalize the circumstances in ways that the translation above does not.]: The Romans, foreseeing troubles, dealt with them at once, and, even to avoid a war, would not let them come to a head, for they knew that war is not to be avoided, but is only put off to the advantage of others.
There is no avoiding war; it can only be postponed to the advantage of others.
Context: The Romans never allowed a trouble spot to remain simply to avoid going to war over it, because they knew that wars don't just go away, they are only postponed to someone else's advantage. Therefore, they made war with Philip and Antiochus in Greece, in order not to have to fight them in Italy... They never went by that saying which you constantly hear from the wiseacres of our day, that time heals all things. They trusted rather their own character and prudence — knowing perfectly well that time contains the seeds of all things, good as well as bad.

“The best way to avoid trouble is to make sure no one wants to trouble you.”
Birgitte Trahelion
(15 October 1994)

“You can look only when the mind is completely quiet.”
2nd Public Talk, Amsterdam, The Netherlands (12 May 1968)
1960s
Source: How to Become President (1940), Ch. 6 : How not to offend anybody

“I prefer you like this, when you're in a foul mood, because you tell the truth.”
Source: The Angel's Game