The Jews were told that they should not think that they were being brought into Eretz Yisrael on their own merit. Hashem was taking them there in order to fulfill the promise which He gave to the Avos (see Devarim 9:5).
The Midrash HaNe’elam adds to this that when the Jews came with Yehoshua to conquer the land, there were many evil forces that tried to stop them with prosecution in heaven. Each day of the week had resistance via these forces until Avraham, Yitzchok, Yaakov, Moshe, Aharon and Yosef each combatted the first 6 days of the week. The only day left was Shabbos and the merit of the tzaddikim who keep Shabbos and uphold the nation allowed for all the evil forces to be subdued. What does this all mean?
Toil to Acquire
Berachos (5a) teaches us, Rabbi Shimon Bar Yochai said: Three great gifts were given from Hashem to the Jews and each of them are only acquired through great yesurim, toil. They are: The Torah, Eretz Yisrael and Olam Habah. Maharal explains that each item builds on the next. The Torah was earned by the Jews in Egypt through their servitude. The main place of kiyum haTorah, fulfilling the mitzvos, is in Eretz Yisrael and thus, the Jews had to earn that as well. The reward for a life lived with Torah observance in the optimal place leads to an acquisition in Olam Habah.
We see that Torah, Eretz Yisrael and Olam Habah are spiritual items that must be earned through real effort. Chazal tell us that it is in the merit of the tzaddikim that the physical world is sustained. “The entire world is supported by Chanina, my dear son” (Berachos 17b). Chazal also say that ultimately it will be in the merit of the tzaddikim, and their suffering in this world, on behalf of the nation, that everyone will thus earn a portion in Olam Habah (See Derech Hashem II:3:8). The mechanism is that of (Sifra, Vayikrah 26:37), “kol Yisrael areivim zeh l’zeh, all Jews are responsible for one another.”
This is the lesson of acquiring the land. The Jews must recognize that it is only in the cumulative efforts of their illustrious ancestors, the blood, sweat, tears and toil which they invested, that has granted them the privilege of entering the land. When one has this perspective, he is humbled and empowered to take in the message and ensure that he taps into our legacy and continue to uphold Torah values for all generations to come.