There is more valour needed not to take up the affair of honor than to conquer in it. When there is one fool ready for the occasion, one may excuse oneself from being the second.

[Estima por más valor el no empeñarse que el vencer. y ya que haya un necio ocasionado, escusa que con él no sean dos.]

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

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 47 (1647) [tr. Jacobs (1892)]
    (Source)

(Source (Spanish)). Alternate translations:

He finds greater advantage in not engaging, than in overcoming: and though some rash blockhead may be ready to begin, yet he has a care not to make a second.
[Flesher ed. (1685)]

He will deem it better courage not to become ensnarled, than to win, and even should the everpresent fool bob up, he will excuse himself on the ground that he does not wish to be another.
[tr. Fischer (1937)]

There is more courage in avoiding danger than in conquering it. He sees that there is already one rash fool, and avoids adding another.
[tr. Maurer (1992)]