Al-Azraq bin Qays says: An imam of ours whose kunyah was Abu Rimthah led us in prayer, and he said: I prayed this prayer, or a prayer like it, with the Messenger of Allah (peace and blessings be upon him). Sayyiduna Abu Bakr and Sayyiduna Umar (may Allah be pleased with them both) used to stand in the first row on his right. A man had caught the opening takbir of the prayer. When the Prophet of Allah (peace and blessings be upon him) had finished the prayer and given the salam to his right and to his left, until we could see the whiteness of his blessed cheek, he (peace and blessings be upon him) then turned around just as Abu Rimthah (meaning the narrator himself) turned. Then the man who had caught the opening takbir stood up to pray (Sunnah or voluntary prayers). Sayyiduna Umar (may Allah be pleased with him) leapt to him, took hold of his shoulder and shook him, then said: Sit down, for the People of the Book were destroyed only because there was no separation between their prayers. The Prophet (peace and blessings be upon him) raised his blessed gaze and said: "O son of al-Khattab, Allah has guided you to (what is right)." This hadith is sahih on the condition of Imam Muslim, but the two Shaykhs did not record it.