Sahl bin Mu'adh bin Anas narrates from his father, Sayyiduna Mu'adh bin Anas (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "This Ummah will remain upon the (correct) Shari'ah as long as three things do not appear among them: as long as knowledge is not taken away from among them, as long as the children of fornication (illegitimate children) do not become numerous among them, and as long as the Saqqarun do not appear among them." The Companions said: O Messenger of Allah! Who are these Saqqarun? He (peace and blessings be upon him) said: "They will be people who will come at the end of time, whose greeting (salam) to one another when they meet will be cursing one another (that is, instead of greeting they will curse)." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but neither of them recorded it in their books.