Musnad Ahmad

It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) once said to Sayyiduna Ka'b bin Ujrah: "May Allah protect you from the rule of fools." He asked, "What is meant by the rule of fools?" The Prophet (peace and blessings be upon him) said: "It refers to those rulers who will come after me. Those who affirm their lies and assist them in their oppression will have no connection with me, nor will I have any connection with them, and these people will not be able to come to me at the Pond of Kawthar. But those who do not affirm their falsehoods and do not assist them in their oppression, they are from me and I am from them, and soon they will come to me at the Pond of Kawthar. O Ka'b bin Ujrah, fasting is a shield, charity wipes out sins, and prayer is a means of nearness to Allah. O Ka'b bin Ujrah, no one whose nourishment is from the unlawful will enter Paradise, and Hell is more deserving of him. O Ka'b bin Ujrah, people are divided into two groups: some purchase their souls and set them free, and some purchase their souls and destroy them."