There is a special avodah called כפיית הרצון - overcoming one's will. On a simple level we experience this constantly because we are all filled will desires that are counter to what is proper and moral and we have to suppress [or repress] and overcome. We want various pleasures of the flesh which would be better if we wouldn't have them in the first place. So of course we receive tremendous rewards for overcoming our base desires but it would have been better had those desires not surfaced in the first place. This is called "זיכוך הרצון" - Purifying our will so that we don't have negative or impure desires. Once we nevertheless have impure desires, we must overcome.
But there are Tzadikim who reach a much higher plateau - their desires are pure and it is not necessary for them to suppress negative desires. But their special avoda of כפיית הרצון is still needed. So Hashem sets up opponents to their derech who blaspheme, degrade and demean them. Then they have the GOLDEN opportunity to engage in כפיית הרצון by remaining silent and not entering into a bitter dispute.
הנעלבים ואינם עולבים שומעים חרפתם ואינם משיבים עליהם הכתוב אומר כצאת השמש בגבורתו!!
[עי' בס' רזי לי עמ' ש"ה]
