Sayyiduna Ziyad bin Labid al-Ansari (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "This is the time when knowledge departs." I said: How can that be, when we have the Book of Allah among us, we teach it to our sons, and our sons will teach it to their sons? He (peace and blessings be upon him) said: "May your mother be bereaved of you, O Ibn Labid! I used to consider you among the most intelligent people of Madinah. Do the Jews and Christians not have the Book of Allah, the Torah and the Injil, among them, yet they derived no benefit from it?"
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5273