Sefer Tiferes Shmuel writes that bnei Yisroel knew that they hadn’t left Mitzrayim due to their own strength. They knew it was because it was Hashem’s will. Moshe Rabenu wrote this for future generations to know that Hashem is the only One who has the power to save people from difficult situations and that everything depends on His will. He was teaching us that we cannot do anything on our own and we must rely on Hashem to provide for us. Once we accept this fact, we can merit salvation and we can experience the holiness of Eretz Yisroel.
This is as is stated in Zohar Hakadosh (Parshas Behar 110B) on the pasuk (Tehillim 37:3): ‘Trust in Hashem and do good, live in the land and see emunah.’ If one wants to live in Eretz Yisroel, he must have strong emunah and bitachon, and he will then be able to benefit from the holiness of the land.