Even in cases of obvious certainty it is fine to yield: our reasons for holding the view cannot escape notice, our courtesy in yielding must be the more recognised. Our obstinacy loses more than our victory yields: that is not to champion truth but rather rudeness.

[Aun en caso de evidencia, es ingenuidad el ceder, que no se ignora la razón que tuvo y se conoce la galantería que tiene. Más se pierde con el arrimamiento que se puede ganar con el vencimiento; no es defender la verdad, sino la grosería.]

Baltasar Gracián y Morales (1601-1658) Spanish Jesuit priest, writer, philosopher

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 183 (1647) [tr. Jacobs (1892)]
    (Source)

(Source (Spanish)). Alternate translation:

Even when you are right, it is good to make concessions: people will recognize you were right but admire your courtesy. More is lost through holding on than can be won by defeating others. One defends not truth but rudeness.
[tr. Maurer (1992)]