It is narrated from Imam Hadi (AS) who said:

A bad human being is the one, who is two-faced and double-tongued; flatters his friend and brother in his presence, but backbites about him which is like eating meat from his body. Such a two-faced person is jealous if his friend is in comfort and peace, and blames him if he is in difficulty and hardship [1].

[1] Beharul Anwaar, Vol. 75, Page 373, Hadith 14.

Source: en.shafaqna.com