Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Khuzaymah bin Thabit (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Beware of the supplication of the oppressed, for it is raised above the clouds (i.e., it is accepted immediately). Allah Almighty says: By My honor and by My majesty! I will surely help you, even if it is after some time."

Sayyiduna Abdullah bin Umar (may Allah be pleased with them) narrates: The Messenger of Allah (peace and blessings be upon him) said: Beware of the supplication of the oppressed, for it rises towards the sky like sparks.

It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Beware of the supplication of the oppressed, even if he is a disbeliever, for there is no veil between it and Allah."