The reciter: The author (may Allah have mercy on him) said in the book
"Mishkat al-Masabih", the Book of Fitnahs, the Chapter on the Signs Before the Hour and the Mention of the Dajjal: It was narrated from al-Nu'man ibn Sam'an that he said:
An-Nawwas b. Sam`a.n told that God's messenger mentioned the dajjal saying, "If he comes forth while I am among you I shall be the one who will dispute with him on your behalf, but if he comes forth when I am not among you a man must dispute on his own behalf, and God will take my place in looking after every Muslim. He will be a youth with curly hair and a floating eye whom I might compare to `Abd al- `Uzza b. Qatan. Those of you who live till his time should recite over him the opening verses of sura al-Kahf [1] (a version having `should recite over him the opening verses of sura al-Kahf , for they are your protection from his trial'). He will come forth on a road between Syria and al- `Iraq and do mischief right and left. Stand firm, servants of God." God's messenger was asked how long he would remain in the earth and replied, "Forty days, one like a year, one like a month, one like a week, and the rest of his days like yours." God's messenger was then asked if one day's prayer would suffice them in that day which would be like a year
ذكر رسول الله صلى الله عليه وسلم الدجال فقال: إن يخرج وأنا فيكم فأنا حجيجه دونكم وإن يخرج ولست فيكم فامرؤ حجيج نفسه والله خليفتي على كل مسلم إنه شاب قطط عينه طافية كأني أشبهه بعبد العزى بن قطن فمن أدركه منكم فليقرأ عليه فواتح سورة الكهف -وفي رواية- فليقرأ عليه بفواتح سورة الكهف فإنها جواركم من فتنته إنه خارج خلة بين الشام والعراق فعاث يميناً وعاث شمالاً يا عباد الله فاثبتوا، قالوا يا رسول الله وما لبثه في الأرض؟ قال أربعون يوماً يوم كسنة ويوم كشهر ويوم كجمعة وسائر أيامه كأيامكم، قلنا يا رسول الله فذلك اليوم الذي كسنة؟ .. Mishkat al-Masabih 5475.