Or HaChaim on Deuteronomy 31:7/אור החיים על דברים ל״א:ז׳

1 כי אתה תבא את העם הזה, "for you will come with this people, etc." Moses did not say תביא, "you will bring this people," seeing it was G'd who would actually bring the people by destroying their opposition. All Joshua was required to do was to march at the head of the people. While it is true that our sages in Sanhedrin 8 drew our attention to the end of our portion (verse 23) where G'd tells Joshua "you shall bring the children of Israel to the land I have sworn to them," the reason that G'd used the expression תביא was to correct the impression Moses' words had left when he said תבא. According to Rabbi Yochanan Moses meant "you and the elders." G'd objected by saying that there can only be one authoritative spokesman per generation, i.e; dabbar echad ledor. To make this point, G'd said to Joshua "you will bring," instead of "you will come." Now that we have that verse we can interpret the verse in which Moses said "you will come" as a reminder that G'd would do the actual "bringing."