It is generally believed that the ahadith were transmitted orally for one hundred years at least. The Zuhri recorded them by order of Calioph 'Umar b. 'Abdul 'Aziz. And in the view of some "scholars", even his recording was lost. Both these assumptions are based on lack of knowledge of the early literary history of ahadith and their literary style. Therefore, the problem of recording of ahadith needs special attention. Meanwhile it ought to be remembered that mere recording of material is not complete guarantee of its safe preservation.
However, a text can be kept fully preserved even without recording. For exampel, even if all the books on the earth were destroyed, the Holy Quran would stille remain safe, because millions of Muslims have memorized it completely or in parts.
M. Mustafa Azimi