Sayyiduna Uqbah bin Amir (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "What I fear most for my Ummah is milk and the Book" (or he said: "the thing I fear most"). It was said: O Messenger of Allah, what is the matter with milk? He (peace and blessings be upon him) said: "They will leave the congregations and abandon the Friday prayers." It was said: O Messenger of Allah, what is the matter with the Book? He (peace and blessings be upon him) said: "It will be opened up for some people, so they will read it and dispute by means of it."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14888