The Shulhan Aruch (Siman 8) states that one should wear his Tallit Katan over his garments. The Torah explicitly required: "U’r’eetem Oto" (and you shall see the Sisit); hiding them under the clothes would seemingly defeat the entire purpose of the Misva. The Hafetz Haim (Rav Yisrael Meir Kagan of Radin, 1839-1933) in his Mishna Berura gives a stinging rebuke to those who are embarrassed by this Misva and wear their Sisit under their garments. He says that it is analogous to someone who received the royal seal from the king to wear proudly, but is ashamed and wears it under cover. He adds that such people are destined to give an accounting for their behavior. Today, the Hasidim do in fact wear their Sisit over their garments.
However, Rabbi Bitan, in his English version of Yalkut Yosef cites testimony that the Hafetz Haim himself wore his Sisit inside, as did his grandson Rav Hillel Zacks. This was also the custom of the Lithuanian Rosh Yeshivas. The source for their practice is Rabbenu HaAri (Rav Yishak Luria of Safed, 1534-1572) and Rabbenu HaRashash, who had a different understanding of the Pasuk. They explain that when the Torah said to "see the Sisit," it only meant when you put them on, and not to have them constantly in view. On the contrary, they rule that it is preferable to keep the Sisit inside. The Hafetz Haim was only criticizing those who put the Sisit inside out of embarrassment; we wear it inside because we follow the tradition of the Arizal. In addition, we all wear a Tallit Gadol, which satisfies the requirement for an outward display of the Misva, whereas in the times of the Hafetz Haim, only married men wore the Tallit Gadol. Therefore, if an unmarried man would put his Tallit Katan under his garments, he would never have any outward display of Sisit. In light of this, no one should feel that they are in "contempt" of the Hafetz Haim by wearing his Tallit Katan under his garment.
The custom of Sepharadim is to not only wear the Tallit Katan under the garments, but to keep the Sisit inside the pants, as well. If a Sepharadi wants to follow the Ashkenazi custom of wearing the strings out, he may do so only under one of the following two conditions: One, If he studies in an Ashkenazi Yeshiva and doesn’t want to stand out. Second, if a person wants to inspire and strengthen himself by wearing the Sisit out, as part of the Teshuva process, he may do so. In both cases, once the special circumstance no longer applies, he must revert to the Sepharadic custom. Harav Ezra Attiah ZT"L, Rosh Yeshivat Porat Yosef, said that if a Sepharadi wears his Sisit out, in principle, just because he wants to adopt the Ashkenazi custom, he is casting aspersions on the great Sadikim and Hachamim of previous generations who wore their Sisit inside. Is he any better than the Kaf Hahaim or the Ben Ish Hai?
SUMMARY
A Sepharadi should wear his Tallit Katan and its Sisit under his garments.
