It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The Dajjal will emerge when there is weakness in religion and knowledge has turned its back. He will have forty days to roam the earth; one day of them will be like a year, one day like a month, one day like a week, and the rest of his days will be like your ordinary days. He will have a donkey which he will ride; the width between its two ears will be forty cubits. He will come to the people and say: I am your Lord! But your Lord is not one-eyed. Between his two eyes will be written 'K F R', which every believer will read, whether he knows how to write or not. He will pass by every water and watering place except Madinah and Makkah; Allah Almighty has made these two cities forbidden to him, and the angels will be guarding their gates." This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs (Bukhari and Muslim) did not record it.