23:1. One is allowed to enter a cemetery while he is wearing tzitzis, so long as he is not crossing over graves [lit. "the tzitzis are not dragged over graves”]. However, if he is crossing over graves, then it is forbidden [f[for him to tzitzis]ecause it would be (1) “mocking the poor.” All of the above was said during the days when tzitzis were placed upon garments that were worn (2) as regular garments [m[meaning, not specifically in order to be wearing tzitzis] In our day, we wear the entire garment in order to fulfill the mitzvah, and therefore it is forbidden to to show the tzitzis even if one is not crossing graves. This is true only when the tzitzis are uncovered [o[outside of the shirt] but if (3) they are covered (inside of the shirt/pants), then it is permitted to have the tzitzis on.
MB 1. Mocking the poor – For it appears that he is taunting those who cannot fulfill the mitzvah (of tzitzis).
MB 2. As regular garments – For at that time the custom was that their clothing was made with four corners [r[regardless of the mitzvah]
MB 3. They are covered – Like one who hides the tzitzis of the large tallis under the corners of his garments. Similarly, if one wears the smaller tallis under his shirt, there isn’t a mockery here since the tzitzis are covered – unless he does not wear an outer garment [t[thereby leaving the tzitzis revealed]in which case he cannot wear the tzitzis unless he pushes them up into the corners [o[of the tzitzis, or his shirt or pants](From the Pre Magadim it sounds like one should be stringent with a large tallis, even if covered, since it is reserved for prayers. However the Bais Yosef does not seem to agree, and so too the Derech HaChaim does not say anything about this, and merely rules that if it is covered, it is permissible.)
23:2. There are those who have the custom of tying two tzitzios (plural of tzitzis) of two corners together when they enter a cemetery, but (4) this practice is no help.
MB 4: This practice – Even though he tied them together, this doesn’t nullify the mitzvah of tzitzis. This is true because it is not a knot that will last, since he has in mind to untie the knot immediately when he leaves the cemetery. This is like that which was written in chapter 10, paragraph 3. [T[This implies that if one permanently ties two tzitzios together, this would invalidate them even though they were initially tied properly onto the garment. 10:3 discussed the case where one sewed up the corners of the garment and rounded one off – but if one were to cut these stitches then the garment would again have four corners. The ruling there is that obviously he intends to remove those stitches, and therefore the garment requires tzitzis. — YM]urthermore, according to those who rule that tzitzis are nullified by tying them, then he is wearing a four cornered garment without tzitzis.
23:3. One who comes within 4 paces (6-8 feet) of a dead person or (5) of a grave (6) has the same law as that of entering a cemetery. (7) In places that have the custom to remove the tzitzis from the tallis of the dead while still in the house, if the pallbearers have on tzitzis, then that should cause us to be concerned about (8) “mocking the poor”.
MB 5: Of a grave – Even when coming close to the coffin of a minor [c[child under bar mitzvah age – who was not obligated to perform the commandments even while alive]one should still be careful of mocking the poor, for perhaps it is the soul of a great person. However, no such problem exists when approaching the coffin of a woman, who during her lifetime was also exempt from this mitzvah. [W[We’re not doing deep philosophy here, but some explanation is needed. Judaism believes in resurrection, in order for a soul to complete its purpose in the world. It is specifically the soul of a great person that might only need a few short additional years, thus dying as a child. The obvious question is that if so, shouldn’t we worry even near the grave of a woman, who might have been a man in a previous life? Answer: resurrections only happen within the same gender. -YM]
MB 7: In places that have the custom: The later commentators agreed that even in a place that does not have the practice of removing the tzitzis, it is also a problem of mocking since the dead are exempt from the mitzvos.