Question: Why do some people customarily wear specifically a wool Tallit Katan (Tzitzit garment)? Is this the proper custom?
Answer: Regarding the Mitzvah of Tzitzit, the Torah states, “And they shall make for themselves Tzitzit on the corners of their garments throughout their generations.” The Gemara (Menachot 39b) states, “It was taught in the study hall of Rabbi Yishmael: Any unspecified garment in the Torah refers to a garment made out of either wool or linen.” The Gemara and Poskim (ibid.) discuss this matter at length.
In that same Gemara, Rav Yehuda and Rav Nachman disagree regarding whether the Mitzvah of Tzitzit likewise applies to only wool garments or if garments made of other materials are also subject to the Torah commandment since the Torah states “On the Tzitzit of the corner” which means from the same material as the corner and garments of all materials must have Tzitzit tied on their corners.
The Rishonim disagree whose opinion the Halacha follows. Rashi, Rabbeinu Tam, and others rule that the Halacha follows Rava who maintains that a garment made of any material is obligated in the Mitzvah of Tzitzit on a Torah level. On the other hand, the Rambam and other Poskim rule in accordance with Rav Nachman that the Torah obligation of Tzitzit applies only to garments made of wool or linen.
The Rambam writes: “A garment which requires Tzitzit on a Torah level is one which has four corners etc. and one that is made of either wool or linen. However, a garment made of other materials, such as silk, cotton, camel or rabbit fur, or goat hair and the like, is only obligated in the Mitzvah of Tzitzit on a rabbinic level in order to be meticulous regarding the Mitzvah of Tzitzit.”
Thus, according to the Rambam, one who wishes to fulfill the Torah commandment of Tzitzit must ascertain that one’s garment is made of lamb’s wool; however, wearing a cotton garment would not qualify for the Mitzvah of Tzitzit on a Torah level and would merely be rabbinic. Nevertheless, according to Rabbeinu Tam, garments made of any material are eligible for the Torah commandment of Tzitzit and one need not specifically wear a wool garment.
Halachically speaking, Maran Ha’Shulchan Aruch, whose rulings we have accepted, rules in accordance with the Rambam’s view that only wool or linen garments are obligated in the Torah commandment of Tzitzit, for this is likewise the opinion of the Rif, Eshkol, Chinuch, and other Rishonim. On the other hand, the Rama rules in accordance with the Ashkenazi custom which follows the ruling of Rabbeinu Tam that there is no distinction between wool and other materials and the Torah commandment of Tzitzit applies to all garments.
Therefore, one who acts stringently and wears specifically a wool garment in order to fulfill the Mitzvah of Tzitzit on a Torah level is certainly praiseworthy. Indeed, the Torah commandment of Tzitzit is tantamount to all of the Mitzvot in the Torah (see Nedarim 25a). If one does not wear a wool garment and instead wears a cotton garment and the like, one only fulfills the Mitzvah of Tzitzit on a rabbinic level. According to the Ashkenazi custom, however, even in this way, one fulfills the Mitzvah of Tzitzit on a Torah level since the Rama rules like Rabbeinu Tam who rules in accordance with Rava who writes that the Torah commandment of Tzitzit applies to garments of all materials. Nonetheless, many Ashkenazi, G-d-fearing men wear specifically a wool garment in order to full the Torah commandment of Tzitzit on a Torah level according to all opinions. This is especially true in the winter when this is no bother at all.
Indeed, Maran Rabbeinu Ovadia Yosef zt”l would wear specifically a wool Tallit Katan during both the winter and summer.
