It is narrated from Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) that Abu Bakr (may Allah be pleased with him) came to the Messenger of Allah (peace and blessings be upon him) and said: O Messenger of Allah! I passed through such-and-such valley and there I saw a handsome and beautiful man performing prayer with extreme humility and devotion. The Noble Prophet (peace and blessings be upon him) said: Go and kill him. Abu Bakr (may Allah be pleased with him) went back to him and found him in the same state; he did not consider it appropriate to kill him, so he returned to the Messenger of Allah (peace and blessings be upon him). Then the Noble Prophet (peace and blessings be upon him) said to Umar (may Allah be pleased with him): You go and kill him. Umar (may Allah be pleased with him) went there and found him in the same state as Abu Bakr (may Allah be pleased with him) had seen him; he also did not consider it right to kill him, and after returning said: O Messenger of Allah! I saw him performing prayer with great humility, so I did not consider it right to kill him. The Prophet (peace and blessings be upon him) said: Ali! You go and kill him. Ali (may Allah be pleased with him) went but did not find him there. Ali (may Allah be pleased with him) returned and said: O Messenger of Allah! I did not see him. Then the Noble Prophet (peace and blessings be upon him) said: He and his companions will recite the Qur'an beautifully, but it will not go below their chests, and they will go out of the religion just as an arrow passes through the bow, and they will not return to the religion until the arrow returns to its bow. You should kill them; they will be the worst of all people.