Anas ibn Malik said, ” I shall tell you a hadith which I heard from the Messenger of Allah (May Allah shower peace and blessings upon him), and which no-one will tell you after me. I heard him say “Among the signs of the Hour will be disappearance of knowledge and the appearance of ignorance. Adultery will be prevalent and the drinking of wine will be common. The number of men will decrease and the number of women will increase until there will be fifty women to be looked after by one man.”"
This hadith was reported in the two Shahihs from the hadith of Abd Rabbihi.
Abdullah said. “The Prophet (May Allah shower peace and blessings upon him) said, “Just before the Hour, there will be days in which knowledge will dissappear and ignorance appear, and there will be much killing.”" (Ibn Majah ; also narrated by Bukhari and Muslim, from the hadith of al-’Amash.)
Hudhayfa ibn al Yaman said , “The Prophet (May Allah shower peace and blessings upon him) said,”Islam will become worn out like clothes are, until there will be no-one who knows what fasting, prayer, charity and rituals are. The Quran will disappear in one night, and no Ayah will be left on earth. Some groups of old people will be left who will say. We heard our forefathers saying La ilaha illa Allah, so we repeat it.”" Silah asked Hudhayfah, “What will saying La ilaha illa Allah do for them when they do not know what prayer, fasting, ritual and charity are?” Hudhayfah ignored him; then Silah repeated his question three times and each time Hudhayfah ignored him. Finally he answered. ” O Silah, it will save then from Hell”, and said it three times. (Ibn Majah), This indicates that in the last days knowledge will be taken from the people, and even the Quran will disappear from the Mushafs and from people’s hearts. People will be left without knowledge. Only the old people will tell them that they used to hear people saying La ilaha illa Allah ; and they will repeat it to feel close to Allah (Glorified and Exalted is he), so it will give them some blessing, even if they do not have any good deeds or beneficial knowledge.
Knowledge will be taken away from men and ignorance will increase during the last days, because Allah will abandon them. They will remain like this, and their ignorance and misguidance will increase until the end, as in the Hadith of the Prophet (May Allah shower peace and blessings upon him): “The hour will not come upon anyone who says Allah, Allah”; it will only come upon the most evil of men.” (The Signs before the Day of Judgement – Ibn Kathir)