Lost and Found

Bemidbar 10,25: The tribe of Don was among the most populous, and brought up the rear in the marching order. The word for rear-guard here is literally “measef – the gatherer.” Rashi suggests that Don’s task was to gather up lost objects that had been dropped during the journey, and restore them to their owners as well as to gather in straying individuals who had become lost or fallen behind.

What zechus did Shevet Don have to merit that they be positioned and assigned to do the mitzvah of returning lost items?

1. Chaza”l explain (Bamidbar Rabbah 2:7) that each shevet had its unique flag, and the flag of Shevet Don contained the emblem of a snake, as Yaakov Aveinu blessed Don by comparing him to a snake. The pasuk states that because the snake persuaded Chava to sin by eating the forbidden fruit, the snake was punished and Hashem created great animosity between the snake and mankind. Rashi explains that the snake attempted to kill Adom in order to take Chava. The Gemara elaborates (Sotah 9b Shabbos 146a) that just as Chava was the aveidah of Adom, it is the natural process for a man to search for his aveidah - his wife. The snake attempted to create distance and separation between man and his aveidah. Therefore, the tikun for the snake is hashavas aveidah, returning lost objects, and Shevet Don, equated to a snake, merited to perform that mitzvah.
2. When Rachel Imeinu did not have children, and there was distance between the aveidah and the baal ha'aveidah, it was Don who effected justice and reconciliation. In this merit, Shevet Don was designated to perform hashavas aveidah in the midbar, resulting in continued reconciliation between the aveidah and the baal ha'aveidah.
3. There are many explanations as to why Don is analogous to a snake (Bereshls Rabbah 99:12; Zohar 243b; Ramban; Rabbeinu Bachya). The Arizal explains (Chumash Ha'Ari Bereshis 49:16) that Don was compared to a snake because Shimshon, from Shevet Don. went after his eyes just as the snake saw Chava and desired her." Possibly, the tikun for Don - who personified the snake - was looking for lost items with discerning eyes.
4. The Michtav Me'Eliyahu elaborates that the mission of Shevet Don was to bring back lost neshamos, as exemplified Shimshon haGibor searched and found lost sinners, returning them to holiness. It would seem fitting that the mission of Shevet Don incorporate returning lost material items as well.
5. There is a limiting halachah regarding the mitzvah of hoshevos oveidah. An elderly person who finds it unbecoming or degrading to return a particular lost object is not obligated to do so. (Bava Metzia 29b; Choshen Mlshpat 263:1) We find that HaShem appointed Betzalel from Shevet Yehudah to lead the building of the Mishkan, and designated Oheli'ov from Shevet Don to serve with him. Rashi elaborates that Betzalel was from Shevet Yehudah, a leading shevet. Oheli'ov was a counterbalance to him because he was from Shevet Don, a downtrodden shevet (as Don was the first shevet not born to Leah or Rochel, the primary mothers). Shevet Don was selected to do hashovas oveidah because it is appropriate that the downtrodden who are of a humble mindset be assigned that task, as the exception of elderly person will occur less frequently by them, resulting in more lost objects being retrieved.
6. Rabbi Zalman Sorotzkin in his book Oznayim LaTorah, answers that it seems to say that the Holy One Blessed be He wanted to grant the tribe of Don mitzvos between man and his fellow, given that they [the tribe of Don] were negligent with mitzvos between man and God. As it is explained (Bamidbar Rabbah 2:6) Don darkened the world by idol worship which Yerovoam carried out when he turned to all of Israel and none would accept the calves, and only the tribe of Don accepted them...and the Holy One Blessed be He, Who does not want to push anyone away, granted Don the mitzvah of saving people and property, and made this tribe “the gatherer” for all the divisions.”
7. Rabbi Michel of Zhlotzov used to begin his prayers very late in the day. When the Jewish people traveled through the desert the tribe of Don was last, behind all the others. Their job was to pick up and return all the lost items that their brethren had dropped along the way. On the spiritual level, their function was to elevate all the prayers that had been uttered without the proper intentions. I am just following their example.
8. Lubavitcher Rebbe: Torah and Judaism in every place, ensuring that no Jew's light of sanctity should be lost. This is particularly relevant to our generation, that of the "footsteps of Moshiach," the last generation of exile, the function of which is to be "gatherer for all the camps" concerning all generations. Simply put, when one meets a Jew who has "lost" holiness, his function is to return it to its owner, by bringing him close to Judaism, Torah and mitzvos. And because this generation is the "gatherer for all the camps," no one else can do it."