At the beginning of Parashat Mas'ei, the numerous journeys of the Bnei Yisrael are recorded. Rashi (BeMidbar 33:1 s.v. Eileh Mas'ei) asks a rather intriguing question on them. Didn’t the Torah already mention where the Bnei Yisrael had encamped? Why are the journeys repeated here?
Rashi presents two possible answers to his question. He determines that there are only twenty encampments throughout the years that the Bnei Yisrael are being punished for the sin of the spies. This is to show that Hashem's kindness is everlasting; the Jews are not wandering from place to place, but have time to rest and regain composure. Rashi's second answer is a Derashah quoted from Rav Tanchuma. He compares it to a king whose son became sick. The king brought his son far away to be healed. On the way home, he related to his son all the places they went and things they encountered. Similarly, as the Bnei Yisrael are going home, Hashem is relating to them all of their journeys. Both of these answers seem to resolve Rashi’s difficulty.
The Lubavitcher Rebbe zt”l comments on Rashi’s answers. According to him, whenever Rashi gives two answers to a question, it is because both have some sort of problem. Let us look at Rashi's first answer. Had the Torah wanted to emphasize the kindness of Hashem, it should have simply stated that the Bnei Yisrael make twenty stops over a period of thirty-eight years. It is not necessary to enumerate the journeys of the first and last years, since those encampments have nothing to do with the period of their wandering. Because of this question, Rashi offers his other answer. The problem with his other answer is that during the retelling of the journeys, at a certain point the Torah simply begins listing the names of the places through which the Bnei Yisrael travel without giving any other details. The reason Rashi presents both answers is because each problem can be fixed using his other answer. The reason the Torah enumerates the journeys, a fact problematic to the first answer, is because of Rashi's second answer, namely, that Hashem wants to remind Bnei Yisrael of all of their journeys that they have endured together. The reason the Torah leaves out details of the later journeys, a fact problematic to the second answer, is because the Torah is showing how few encampments the Bnei Yisrael have during the thirty-eight years in the Midbar. Thus, the problems we had with Rashi can be ameliorated, and both answers can be interrelated.