Daas Torah page 284
Pnei Yehoshua (Berachos 5a): If one can not find a sin that justifies the suffering then it is suffering of love. Rashi explains that Gd afflicts undeserved suffering in order to increase the reward in the World to Come. Why should Gd afflict the tzadik when there is no need for the suffering - since no person would torture his friend in order to give him extra presents. And the question seem even stronger since all the worlds belong to Gd and He can freely give them to whomever He wants. Furthermore this gemora also states that the World to Come is only given through suffering. Why should this be? An obvious answer is that the soul is not capable - even after it has separated from the body - to receive the light of the transcendent World to Come without suffering…. However this explanation doesn’t fit the language of Rashi that the purpose is to receive greater reward than his merit. The explanation of Rashi could be that the undeserved suffering is to atone for the sin of other Jews as we see in Sanhedrin (39a)… Thus Gd does not want the world destroyed. If he brings suffering on the average person it is possible he won’t accept the suffering willingly and will rebel - Heaven forbid! Therefore He brings the suffering on the righteous who are willing to accept it with love for the sake of all Jews. Since this tzadik brought merit to the masses by his suffering, he receives his own reward and also their reward in the World to Come. He also obviously receives the portion of the wicked who have lost their portion in the World to Come. This latter explanation seems to be the understanding of Rashi while the original explanation seems to better fit the language of the gemora.
Pnei Yehoshua (Berachos 5a): If one can not find a sin that justifies the suffering then it is suffering of love. Rashi explains that Gd afflicts undeserved suffering in order to increase the reward in the World to Come. Why should Gd afflict the tzadik when there is no need for the suffering - since no person would torture his friend in order to give him extra presents. And the question seem even stronger since all the worlds belong to Gd and He can freely give them to whomever He wants. Furthermore this gemora also states that the World to Come is only given through suffering. Why should this be? An obvious answer is that the soul is not capable - even after it has separated from the body - to receive the light of the transcendent World to Come without suffering…. However this explanation doesn’t fit the language of Rashi that the purpose is to receive greater reward than his merit. The explanation of Rashi could be that the undeserved suffering is to atone for the sin of other Jews as we see in Sanhedrin (39a)… Thus Gd does not want the world destroyed. If he brings suffering on the average person it is possible he won’t accept the suffering willingly and will rebel - Heaven forbid! Therefore He brings the suffering on the righteous who are willing to accept it with love for the sake of all Jews. Since this tzadik brought merit to the masses by his suffering, he receives his own reward and also their reward in the World to Come. He also obviously receives the portion of the wicked who have lost their portion in the World to Come. This latter explanation seems to be the understanding of Rashi while the original explanation seems to better fit the language of the gemora.