Reviewing maamarim publicly; the tallis katan which the Jews wore during the time they wandered in the desert

[E.g., it is customary on certain occasions for chassidim to gather together and for one person to recite a maamar by heart. Often, those reciting the maamar focus on saying the maamar correctly without paying too much attention to whether it is understood by the listeners or not. The person to whom the letter is addressed wrote to the Rebbe, asking whether it was desirable that attention be paid to the listeners understanding as well.]

[Which at that time was understood by more people than Lashon HaKodesh, the language in which maamarim are traditionally written.]

[Who were seen (as reported in Bava Basra 74a), lying in their graves wearing tzitzis. As Tosafos explains, every Tishah BeAv, they would go to sleep in their graves. Since they were wearing tzitzis when they went to sleep, their corpses were seen with tzitzis.]

[I.e., in that era, it was common to wear four-cornered garments on which one was required to place tzitzis as part of one’s ordinary garments. In a later era, wearing four-cornered garments was no longer common. In order to promote the observance of the mitzvah of tzitzis, our Sages ordained that a special garment — a tallis katan — should be worn.]

[For it is not appropriate for a corpse to be buried unclothed, and they were expecting to die.]

[See Pri Etz Chayim, Shaar Tzitzis, ch. 1; Magen Avraham 21:2.]