Imaam Maalik (May Allah always bless him, Ameen) said: I noticed people who seemed to be faultless and were considered to be good people, only to later notice them disclosing the faults of others. As a result of this (evil trait), people started finding faults in them.

I also noticed people who seemed to be bad and sinful people. But by them refraining from exposing the faults of others, Allah concealed their faults.
(A’faatul Lisan: Sheikh Muhammad Shanqiti)