Serious Infraction

The Chovos Halevavos says something simply frightening [based apparently on a Medrash]. If Reuven speaks lashon hara about Shimon, Reuven passes on to Shimon his mitzvos and receives in return Shimon's aveiros. What is the rationale behind this? We don't find this stated about any other aveira.

The Michtav Me'eliyahu in volume 4 page 20 and 213 attempts to explain, but with all due respect to the revered author - I am not convinced that his explanation is the correct one.

So if anybody has anything else to offer - I'd love to hear.

But what is clear is that lashon hara should be avoided at all costs. The halacha is that one must give up all of his money [if need be] in order not to speak lashon hara.