Answer: Of course, it is called Lashon HaRa – evil tongue.
It kills everything between the friends. If I speak behind my friend’s back, I betray the Creator. I cheat on Him. There can be nothing else here. After all, the Creator puts the ten with all of its problems before me. Behind a friend’s back, we can only talk about how to help him and about nothing else.
From the Convention in Vilnius “From Chaos to Harmony,” Day One 11/3/17, Lesson 1