“They ask thee about the (final) Hour - when will be its appointed time? Say: ‘The knowledge thereof is with my Lord (alone): none but He can reveal as to when it will occur. Heavy were its burden through the heavens and the earth. Only, all of a sudden will it come to you.’ They ask thee as if thou were eager in search thereof: say: ‘The knowledge thereof is with Allâh (alone), but most men know not.’ ” (al-A‘râf 7:187)
Anas ibn Malik said, "I shall tell you a Hadîth which I heard from the Messenger of Allâh, and which no-one will tell you after me. I heard him say, 'Among the signs of the Hour will be the 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.''
Abdullâh said, "The Prophet said, 'Just before the Hour, there will be days in which knowledge will disappear and ignorance will appear, and there will be much killing.' " (Ibn Majah; also narrated by al-Bukhârî and Muslim.
Hudhayfah ibn al-Yaman said, "The Prophet said, 'Islâm will become worn out like clothes are, until there will be no-one who knows what fasting, prayer, charity and rituals are. The Qur'ân 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 fathers saying La ilaha illa Allâh, so we repeated it.' Silah asked Hudhayfah, "What will saying La ilaha illa Allâh 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 Hudayfah ignored him. Finally he answered, "O Silah, it will save them from Hell", and said it three times. (Ibn Majah)