SHAFAQNA – It is narrated from Imam Al-Hassan Al-Askari (AS) who said: The one who has two faces and two tongues is a bad person; such person, praises friends and brothers when they are present, but says bad things and reproaches them in their absence, this act is like eating their flesh. When the two-faced person sees friends and brothers in comfort and prosperity, becomes jealous; and if sees them in discomfort and hardship, reproaches them [1].
[1] Mostadrakul Wasael, Vol. 12, Page 261 & Beharul Anwaar, Vol. 75, Page 401