Rambam - 1 Chapter a Day

Water that was drawn using a container and then used by humans to fill a pool.

A log is 344 cc according to Shiurei Torah and 600 cc according to Chazon Ish.

See also Hilchot Mikveot 10:6-8.

In his Commentary to the Mishnah (Zavim 8:12), the Rambam speaks about this decree as a safeguard for terumah. It does not appear to apply to ordinary foods.

Our text is based on the Shabbatei Frankel printing of the Mishneh Torah. The standard printed text has a slightly different version whose meaning is problematic.

Note the parallels to Chapter 8, Halachah 10.

I.e., an acceptable mikveh had to contain water that was not drawn by humans. In the eras before advances in plumbing revolutionized the construction of mikvaot, the water in kosher mikvaot would often stand for lengthy periods of time and become stagnant and foul. This was particularly true in the summer in lands like Eretz Yisrael where for at least six months of the year, there is no rainfall.
Today, these problems are usually avoided by constructing mikveot with two pools: one in which rainwater is collected, which is set off from the pool in which people immerse, and one in which the immersion is made which is repeatedly drained and refilled to keep the water fresh. The two pools are then connected through the halachic convention known as hashakah. See Hilchot Mikveot, ch. 8.

I.e., unlearned people who observed Jewish Law without knowing its underlying halachic rationales.

Thus it was possible that the immersion would not be acceptable.

Since he is pure, the immediate rationale for which this safeguard was ordained does not apply.

On the basis of the wording of Zavim 5:12, Tosafot (Shabbat 13b) maintains that three lugim of drawn water impart impurity to a pure person only directly after immersion. Here, and in his Commentary to the Mishnah, the Rambam makes no mention of this qualification.

As is necessary after immersion to purify oneself from Scriptural impurity. See, however, Chapter 10, Halachah 2, and notes.

See parallel rulings in Hilchot Mikveot 5:1. There the Rambam emphasizes that the ruling applies to water that falls unintentionally. If the water is added intentionally, it disqualifies the mikveh even if it was added from many different containers. He does not qualify his ruling in that manner here.

Similar concepts apply with regard to the second and the third.

Gittin 16a discusses this question and leaves it unresolved. Since a point of Rabbinic Law is involved, the Rambam rules leniently (Kessef Mishneh).

And like all liquids that become impure, is considered a primary derivative of impurity, as stated in Halachah 1 (Chasdei David).

From Shabbat 14a, the Rambam’s source, it is clear that this stringency applies only to scrolls of the Written Law. In later generations when it was already customary to write down teachings of the Oral Law, this decree was not extended to include them.

That sought to eat the terumah.

I.e., as a safeguard against the sacred texts being destroyed.

Chapter 8, Halachah 1.

In his Commentary to the Mishnah (Yadayim 3:3), the Rambam writes that this decree was enacted to reinforce the decree that the Scriptures impart impurity to terumah.

These straps and the margins of the scrolls are not holy in and of themselves. Nevertheless, while attached to the tefillin or the Torah scroll, they are given that status.

See Hilchot Sefer Torah 9:2 which prescribes standard measures for margins to be left for Torah scrolls.

I.e., and not after they have been cut off. Compare to Hilchot Shabbat 23:7.

As the Rambam writes in his Commentary to the Mishnah (Yadayim 3:5, see also Rashi’s Commentary to the verse in Numbers), the two verses cited are sometimes considered as an entire book of the Torah. [For this reason, they are set off by reversed nunnim in a Torah scroll.] According to this reckoning, there are seven — not five books — of the Torah; Numbers is counted as three. Since this amount of letters is considered as a scroll, if a parchment has these many letters, it is also given the status of holiness. Note a parallel in Hilchot Shabbat 23:28.

Even though these books appear as words of wisdom, they were inspired by the Divine Spirit of Prophecy and have the same status as the other books of the Bible. See Megilah 7a.

From Chapter 4, verse 7 to Chapter 6, verse 19.

Chs. 2-7.

In his Commentary to the Mishnah (Yadayim 4:5), the Rambam writes that Ivri “is a script that the Samaritans use to write their Torah scrolls. The script that we use to write our Torahs is the Ashuri script. It is the script with which God wrote the Torah. The name ashuri implies greatness and glory.”

I.e., they do not possess the holiness of sacred texts.

See Hilchot Tefillin 1:19 where the Rambam describes the ink required.

For, as stated in Hilchot Sefer Torah 7:14, it is forbidden to write passages from Scripture on scrolls. Instead, an entire book must be written on one scroll.

Psalms 113-118.

Deuteronomy 6:4-9.

For they contain more than 85 letters.

For a Torah scroll must be sewn together with threads made from animal sinews (Hilchot Sefer Torah 9:13).

Because they are connected to a Torah scroll.

Texts similar to our siddurim (Rashi, Shabbat 115b; see Hilchot Shabbat 23:27).

Since these are not scrolls, they are outside the scope of our Sages' decree.

For they do not have the holiness of a Torah scroll. Indeed, they must be burned, as stated in Hilchot Tefillin 1:13.

A woman suspected of infidelity. She was taken by her husband to the Temple where a scroll on which the biblical passage describing the test she undergoes was written and then placed in water. After the letters were erased in the water, she was given the water to drink. If she was indeed guilty, she would die (see Numbers, ch. 5).

And thus it is not a permanent document.