In Moshe’s final speech to the nation, having fulfilled his duties, he informs them of what will be later. He says:
ה אֱלֹהֶיךָ הוּא עֹבֵר לְפָנֶיךָ, הוּא-יַשְׁמִיד אֶת-הַגּוֹיִם הָאֵלֶּה – Hashem, your G-d; He will cross you over, He will destroy the nations before you. (31:3)
The emphasis on הוּא, that “He” will do it, seems strange, and the fact it is said twice is even stranger.
The Ohr HaChaim explains that the Jews were worried that on losing Moshe, they would further lose two abilities he had; first, that he could and would intercede on their behalf, such as with the Golden Calf, where his intercession ended the plague and prevented their destruction; and second, that he would not be leading them in the wars they would inevitably fight on entry into the Land of Israel.
Moshe addressed the first concern by telling them that הוּא עֹבֵר לְפָנֶיךָ – the same word is used to describe Hashem’s capacity to forgive – עובר על פשע. Moshe explained that in reality, it had been Hashem all along, that He had aroused the idea of praying for the Jews in Moshe, and that capacity to be forgiven would remain, since Moshe had been an instrument for Hashem’s forgiveness, and not the cause.
Regarding the second, Moshe expressed the same idea – it had never been him – הוּא-יַשְׁמִיד אֶת-הַגּוֹיִם הָאֵלֶּה – Hashem had been with them all the time, and would remain so.
The Seforno explains the whole speech as conveying this message – that they had Hashem watching over them, and it would be better for them to experience Hashem directly than via himself as a conduit.
Sometimes people are averse to recognising their own abilities, and they don’t feel capable of rising to a challenge without their teachers. Moshe was telling the Jews that after 40 years of preparing, they were finally ready to become what they left Egypt to be. We too need to recognise that eventually, the training wheels have to come off.