Musar su Salmi 103:9

The fifth - "He does not hold on to His fury forever" - this is a different trait: that even if a person holds on to his sin, the Holy One, blessed be He, does not hold on to His fury. And if He holds on to it, not forever. Rather, He nullifies His anger, even if the person does not repent. As we found in the days of Yerovam the son of Yoash, that the Holy One, blessed be He, brought back the boundary of Israel [from occupation] and they were [still] worshipping calves - He had mercy upon them, but they did not repent. If so, why did He have mercy? For the sake of this trait, that He does not hold on to his fury forever. Just the opposite, His fury weakens - even as the sin is still in existence, He does not punish, but rather He expects and has mercy that they may repent. And that is [the meaning of] "He will not contend forever, or begrudge for all time" (Psalms 103:9). Rather, the Holy One, blessed be He, acts with softnesses and harshnesses, all for the good of Israel.