The evidence for it being recommended includes the hadith related by Hakim and Bayhaqi, from Abu Sa`id (Allah be pleased with him), "Whoever recites Surat al-Kahf on Friday, light shall shine forth for him between the two Fridays." [Ibn Hajar, Talkhis al-Habir] It is recommended to recite Surat al-Kahf completely the night before Friday, and it is also recommended to do so Friday itself, before Maghrib time. Ibn Abidin said, "And it is best to do so early on Friday, in order to rush to the good and to avoid forgetting." [Ibn Abidin, Radd al-Muhtar, "Bab al-Jumu`ah"] http://qa.sunnipath.com/issue_view.a...&ID=782&CATE=3