Why does the Torah repeat here the command that Hashem already issued above in Pasuk 11?
Rashi and Rashbam: In fact, this is synonymous with Hashem's command in Pasuk 11. 1
Ramban (on Pasuk 13) 2 : Moshe now assumed that, from now on, he together with Aharon would prophesy and would perform all the miracles before Yisrael and before Par'oh, and that Aharon would be the spokesman. But Hashem said to him "Ani Hashem" - reminding him that it was to him alone that Hashem revealed His great Name, and that he alone was the Shali'ach who would issue Par'oh with instructions. 3
Why did Hashem add the words " ... Kol asher Ani Dover Eilecha"? Why might Moshe otherwise not have done so?
Oznayim la'Torah #1: Having in mind Moshe's Eimas Malchus
See Oznayim la'Torah.