Tractate Tefillin

It is not permitted to write [the four scrolls of] tefillin on skins of ritually unclean cattle or on skins of ritually unclean wild animals. It is permitted, however, to write them on skins of nebeloth and ṭerefoth and there is no need to consider the possibility of their having been pierced at the animal’s heart.

If [tefillin scrolls] were perforated, they become unfit for religious use [if the hole occurred] in the written part; but if it occurred in the margin they remain fit. If the letter waw was shaped like a zayin or vice versa, straight-lined letters like curved ones or vice versa, open letters closed or vice versa, or if the shape of their letters had been altered [in any other way], or if they were written in [obsolete] Hebrew, or were made as a kind of amulet—they are unfit for religious use.

Women, slaves and minors are exempt from [the commandment of] tefillin. A minor who knows how to take care of his tefillin is subject to the law of tefillin. It is related that Ṭabi, R. Gamaliel’s slave, used to put on tefillin; Michal, Saul’s daughter, used to put on tefillin; Jonah’s wife used to make the festival pilgrimages to Jerusalem.