We can disagree without being disagreeable
I always credit Dick Stafford with the "We can disagree without being disagreeable" quote*.
Dick Stafford had the opportunity to disagree with many people while serving for years as the auditor/treasurer of Washington County and later as a county commissioner. As Dick would say, disagreement isn't bad. In many ways, disagreement is good. Through an exchange of thoughts and ideas, better solutions surface. When you take the time to hear people out, it expands your own thinking.
* In fact I believe the quote is "To disagree, one doesn't have to be disagreeable." by Barry Goldwater