Question: Must a Jew’s tzitzit strings hang on the outside of his pants?
Answer: The Mishnah Berurah (Orach Chayim 8:26) writes, “Those people who place their tzitzit inside their trousers act improperly. It is not enough that they ignore the fact that it is stated [in the Torah] ‘and you shall see it and remember,’ but in addition they show contempt for the mitzvah of Hashem…. They will be accountable for this in the future.…
“If they would have received some gift from a king of flesh and blood on which the name of the king is engraved, how proudly would they always adorn themselves with it in front of other people. All the more so should they wish to adorn themselves with tzitzit, which alludes to the name of the supreme king of kings, the Holy One blessed be He.”
Not all poskim agree, however. The MaHari Beruna, a 15th century revered sage, ruled that only a great scholar or an especially pious person may wear tzitzit on the outside of his garments. Anyone else who does so is acting arrogantly, in effect proclaiming that he observes all the mitzvot of the Torah (based on the drashah that the gematria of tzitzit, plus the number of knots and strings,adds up to 613). This is hubris and improper behavior. A Jew should be modest and not attempt to show everyone how righteous he is.