Is it permissible for a Muslim to supplicate for revenge against those who support an oppressive faction of Muslims, even if only in their heart, knowing that people are divided and unable to discern the truth?

There is no doubt that supporting oppressors, aiding them, and being content with their injustice are among the gravest sins, as Allah Almighty says: {And do not incline toward those who do wrong, lest the Fire touch you.} (Hud: 113). Inclining toward them means being pleased with their actions.

As for supplicating against those who support and aid oppressors: - It is permissible to supplicate against them in a general sense, such as: "May Allah curse the oppressors." - The matter differs when supplicating against specific individuals. If someone is ignorant, misguided, or merely imitative, and does not comprehend the true nature of the injustice, then they do not deserve to be supplicated against. - However, if someone clearly recognizes the injustice and then accepts it and supports them, then they are legally accountable and deserve the warning. Supplicating against such a person is permissible according to some scholars, while others forbid it. Nevertheless, the prophetic narrations (hadith) indicate permissibility. - If someone is actively participating in the injustice through assistance or similar actions, then the legitimacy of supplicating against them is clearer, for they are oppressing people. - If one's situation is unknown, it is possible to supplicate against them with a conditional supplication, such as saying: "O Allah, if so-and-so has wronged me, then deal with him as he deserves." The most complete and preferable approach is to use comprehensive supplications, such as the supplication of Umar ibn Abd al-Aziz: "O Allah, rectify whoever's rectification brings rectification to the Ummah of Muhammad (peace be upon him). O Allah, destroy whoever's destruction brings rectification to the Ummah of Muhammad (peace be upon him)."