Musar su Esodo 17:14

They commenced sinning by considering their personal standing in the community. What concerned them was that Joshua was among those who had been selected to be spies. We know of Joshua that he never moved from the tent of Moses, was his personal valet, etc. (compare Exodus 24,13, and 33,11). The spies reasoned that his inclusion could only be because he would lead Israel in battle to conquer the Holy Land, and that on account of this Moses had also sent him on this mission. G–d had done something similar when He had told Abraham to traverse the land of Canaan (Genesis 13,17), since it would be given to his descendants. Abraham was to be a model for his children, etc. This thought had occurred to the spies only after they had heard Eldad and Meidad prophesy about Moses dying and Joshua leading the Jewish people. This is the reason this portion follows the report of the selection of the seventy elders without an introduction about Israel having requested this mission, as reported in Deuteronomy. Rashi had pointed out already in Exodus 17,14, when G–d instructs Moses to “put it in the ears of Joshua,” that there will be an ongoing war between G–d and Amalaek, but that G–d will wipe out every vestige of Amalek. The reason it was necessary for Joshua to know all this first hand, was a hint to Moses that Joshua would one day become the leader. The eventual mission of the spies was already being prepared at that time.