ש"פ ב' אב - שמחה ביסורי הגוף ותועלתה הרוחנית

Chapter 12: The reason for joy in bodily suffering is because it is a great and tremendous benefit for the sinning soul, cleansing it in this world and saving it from purification in Gehinnom. (Especially in our generations, when it is not possible to fast as many times as prescribed by the fasts of teshuvah from the AriZal, which are necessary to cleanse the soul and save it from purification in Gehinnom.) As the Ramban writes in his introduction to his commentary on Iyov, even Iyov's seventy years of suffering do not compare at all to the suffering of the soul for even one hour in Gehinnom, since earthly fire is only one-sixtieth, etc. Rather, since this world is built on kindness, through light suffering here one is saved from severe judgments of the World to Come.

This is like the analogy of moving a shadow on earth by a handbreadth, which corresponds to moving the sun's orbit thousands of miles across the sky. And even more so—without end—is this true regarding the concept of the chain-like descent of worlds from their highest levels down to this physical world. As is known from what is written in Zohar about the elevation of upper worlds through an awakening from below when offering even a single bird or dove on the altar or a handful of meal offering. The same applies to all practical mitzvos, as known from the AriZal.

And so our Sages said regarding "You shall sanctify yourselves and be holy": if a person sanctifies himself a little below, he is sanctified greatly above, etc. (As explained earlier regarding "Who has sanctified us with His commandments," referring to sovev kol almin, etc.) This very principle applies to reward and punishment as our Sages said: "The reward for a mitzvah is a mitzvah," etc., as explained elsewhere. An understanding person will easily grasp this and one who contemplates will find good.

Summary

The Rebbe teaches that enduring physical suffering with joy purifies one's soul far more gently than spiritual suffering would after life. Even small acts or hardships here have immense spiritual effects above, highlighting G‑d's kindness and encouraging us to embrace challenges with faith.