Yadayim 3:4 - 3:5

שמלמעלן ושמלמטן (the upper and lower margins) - that he (i.e., the Scribe) needs to leave free without writing above from the column [in the parchment] three fingerbreadths and one handbreadth below.

שבתחילה ושבסוף – at the beginning of the Scroll he needs to leave free in order to roll all of the Scroll, meaning to say, like the measurement of the circumference of the entire Scroll, that the Scroll, when t is rolled from its end to its beginning is similar to a Mezuzah when they fold it from [the word] אחד/[“God is] one,” directed towards the שמע/[first word of the] Shema. And at its conclusion in order to roll up the scroll of the Law around a cylinder (i.e., a handle). And especially when he doesn’t have anything there other than the Torah alone, he needs to do this, but when he fastens the [text of the] Torah, [the text of] the Prophets and [the text of] the Writings together, he needs to roll up the all of the Scroll at its end, in order to roll the cylinder at its beginning. But if he rolls it towards its beginning, it is found that the Torah (i.e., Five Books of Moses) is from the outside, and it is disgraceful that that Torah should be made into a guardian for the Prophets and the Writings. And it is this that we are speaking f in the first chapter of Bava Batra [13b-14a] and he makes it in order to roll [enough blank parchment wrapped around a cylinder from its beginning and in order that there be a circumference of the Scroll at its end.

כפרשת ויהי בנוסע הארון – because since that portion (Numbers 10:35-36) is considered like a Scroll (i.e., book of the Torah) by itself. And similarly, they stated in the Midrash Yelamdenu [regarding] (Proverbs 9:1): “[Wisdom has built her house,] She has shewn her seven pillars,” these are seven Scrolls of the Torah, since the book [of] “And God spoke” (i.e., referring to the Book of Numbers) was divided into three parts, and [there are] four other books (i.e., Genesis, Exodus, Leviticus and Deuteronomy), hence there are seven [books of the Torah]. (see Talmud Shabbat 116a and especially the first Tosafot that explains this Midrash on how the Israelites left Mount Sinai in a desire to discard their learning.)

מגילה שכתוב בה – that is to say a writing sheet [which contains several columns] of a Torah scroll, since eighty five letters were written in it, it became sanctified and defiles the hands.

Kohelet does not render the hands impure. This is because its wisdom is [King] Solomon's, and was not said through divine revelation:

כדברי בן עזאי כך נחלקו וכך גמרו – and this is the Halakha.