If one was reading a book [of Scripture] on the threshold [and] the book rolled from his hand, he may roll it to himself. If he was reading on top of the roof and the book rolled from his hand, as long as it has not yet reached within ten fists [of the ground], he may roll it to himself; once it has reached ten fists, he should turn it over on its writing. R’ Yehudah says: Even if it is only removed from the ground by the width of a needle, he may roll it to himself. R’ Shimon says: Even on the very ground, he may roll it to himself; for no Rabbinically prohibited matter may stand in the way of the Holy Scripture.