Halakhah sobre Êxodo 13:9

It is written “In order that God’s Torah shall be in your mouth” (Exod. 13:9), and we explain that one may only write sifrei Torah, tefillin and mezuzot on skins from ritually pure animals and birds (hairs and sinews are also only fit if they come from these species) which are permitted for food. They are fit even if they weren’t killed in a ritually acceptable manner, and even if they were perforated or mutilated, because when we say “permitted for food” we mean in terms of the species, to exclude the various kinds of ritually impure species. Although fish-skin is ritually pure, we don’t write on it, because of the filth, which does not come away during processing. The skin of an embryo counts as skin for this purpose, and we may write sifrei Torah, tefillin and mezuzot on it. This is the best kind of skin. After that, bird skin, and after that the skin of wild animals, the skin of domesticated beasts, and animals which died naturally.

That is that He commanded us to put on the hand tefillin. And that is His saying, "And you shall tie them as a sign upon your hand" (Deuteronomy 6:8). And this command was already repeated four times. And the proof that the head tefillin and the hand tefillin are two commandments is their saying in the Gemara (Menachot 44a) in surprise at one who thinks that one not put on the head tefillin or the hand tefillin without the other, but rather only if they are both together - and this is the language of the statement - "one who does not have two commandments, should he also not do the one commandment?" This means to say, should one who cannot do two commandments not do the one - that is not the case, but rather he should do the one commandment that presents itself. Hence he should put on either one of them that presents itself to him. Behold it has been made clear to you that they called the hand tefillin and the head tefillin, two commandments. And these two commandments are not obligatory for women on account of His, may He be exalted, saying, as a reason for their obligation, "in order that the Torah of the Lord may be in your mouth" (Exodus 13:9) - and women are not obligated in Torah study. And so did they explain in the Mekhilta. And likewise did they explain all the regulations of these two commandments in the fourth chapter of Menachot. (See Parashat Bo, Vaetchanan and Ekev; Mishneh Torah, Tefillin, Mezuzah and the Torah Scroll 1.)

Behold, they elucidated that even the lulav and the sukkah and tefillin - that He commanded that they be "a sign upon your arm and a commemoration between your eyes [...] that the Lord took you out of Egypt with a strong hand" (Exodus 13:9) - are not for the honor of God, may He be blessed, but [rather] to have mercy on our souls. And they already set this into the prayer of Yom Kippur, "You have separated man from the start and recognized him to stand in front of You, as who will say to You what to do, and if he is righteous, what will he give to You?" And so [too], it stated in the Torah (Deuteronomy 10:13), "for your good"; and so [too] (Deuteronomy 6:24), "And He commanded us to do all of these statutes [...], for our good all of the days." And the intention in all of them is that it be good for us and not for Him, may He blessed and elevated. But all that we are commanded is [so that] our souls be refined and purified without the dross of evil thoughts and disgusting character traits. And so that which they said (Berakhot 33a), "[It is because] he makes the traits of the Holy One, blessed be He into mercy and they are only decrees," is to say that God did not worry about the nest of the bird and His 'mercy did not reach' it and its child; as His mercy does not extend to creatures with an animal soul, to prevent us from doing what we need to them. As were it so, slaughtering would be forbidden. But [rather], the reason for the proscription is to teach us the trait of mercy and that we not become cruel. Since cruelty spreads in the soul of a man, as it is known with butchers that slaughter large oxen and donkeys, that they are 'people of blood,' 'slaughterers of men' [and] very cruel. And because of this they said (Kiddushin 82a), "The best of butchers are the partners of Amalek." And behold, these commandments with animals and birds are not mercy upon them, but [rather] decrees upon us, to guide us and to teach us the good character traits. To here are the interpretations of Ramban, may his memory be blessed.