It has been reported through a series of memoirs that Imam had never attended a gathering where there could be possibility of committing any type of sin or backbiting from very early of his youthhood.
Imam had always cut the talks if there had been a back-biting of any individuals.
Imam showed strongly disliked sins, backbiting or any other anti-social behavior.
(A memoirs by Seyyed Ahmad Khomeini, Imam’s son)