It is a matter of great importance to make our conversation agreeable. To do so it is necessary to appear humble, patient, respectful, cordial, yielding in all lawful things and to all. Above all, we must avoid contradicting the opinion of any one, unless there should be an evident necessity for it. In that case, it should be done with all possible mildness, and with the greatest tact, without outraging the feelings of the other party. In this way, contests will be avoided, which produce only bitterness, and which ordinarily spring rather from attachment to our own opinion, than from love for truth. Believe me, that as there are no dispositions more inimical to human society than those which are given to contradiction; so there is not a person more generally loved than he who contradicts no one. -St. Francis de Sales
St. Vincent de Paul was never heard to contend or dispute about indifferent things, but took the word of others with all facility, and adapted himself to their views.
We read of St. John Berchmans that he never quarrelled with any one. For this reason, all his companions not only loved him tenderly, but allowed themselves to be admonished and ruled by him, as if he had authority over them.
Self-love and pride are what lead us to sustain our opinions against those of our neighbor, and thus cool the love we owe him. -St. Vincent de Paul
Text from A Year With the Saints (New York: P.J. Kenedy & Sons, 1891).