Musnad Ahmad Hadith 14441

It is narrated from Jabir (may Allah be pleased with him) that the Prophet (ﷺ) once said to Ka'b bin Ujrah (may Allah be pleased with him): "May Allah protect you from the rule of fools." He asked, "What is the rule of fools, what is meant by it?" The Prophet (ﷺ) said: "By this is meant those rulers who will come after me, who will not follow my way and will not adopt my Sunnah. Those who affirm their lies and assist them in their oppression, they have no connection with me and I have no 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 lies 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 erases sins, prayer is a means of nearness to Allah, or he said, it is a proof. O Ka'b bin Ujrah! No being whose nourishment is from the unlawful will be able to enter Paradise, and Hell is more deserving of him. O Ka'b bin Ujrah! People will be divided into two groups: some will purchase their souls and free them, and some will purchase them and destroy them."