It is narrated from the Prophet of Islam (PBUH) who said:

When the religious duty of “Amr Bil-Ma’arouf wa Nahi Anil-Monkar; enjoining good and prohibiting bad” is abandoned and consequently the pure and good from my Ahlul Bayt (AS) are not followed, Allah (SWT) will allow the worst persons to dominate the people, and at that time even reciting prayers (Duas) will be ineffective and are not accepted (by God) [1]. In another narration, the Prophet (PBUH) said: The most popular (liked) Jihad with God, is to say the word of the Truth in front of the oppressive leader [2].

[1] Tohaful Oqool, Page 51.

[2] Kanul Ummal, Hadith 5576.

Source: en.shafaqna.com