Mishneh Torah, Book of Love: On Writing Scrolls

Laws of Tefillin, Mezuzah, and Sefer Torah, 8:4–5

As in all the scrolls I have seen, I noticed serious incorrectness in these regards, while authorities on the Masorah, who write treatises and compilations with the aim of pointing out the sections that are closed and those that are open, differ according to the variations in the scrolls on which they rely, I deemed it fit to write here a list of the sections which are closed and those which are open, as also the forms in which the songs of the Pentateuch are written so that all the scrolls may be corrected from and compared with them. The copy on which I relied is the well-known Egyptian codex which contains the twenty-four books of the scriptures and which had been in Jerusalem for several years—used as the standard text for the examination of scrolls. Everyone relied upon it because it had been examined by Ben Asher, who closely studied it for many years and examined it again whenever it was being copied. This codex was the text upon which I relied in the scroll of the Law that I wrote according to the rules.