Why does it repeat here Moshe's response that it already recorded in Pasuk 12?
Rashi and Rashbam: This Pasuk too, is synonymous with Moshe's response in Pasuk 12.
: Moshe actually repeated his complaint that he was unworthy to be the Shali'ach to speak to Par'oh.
Refer to 6:29:1:1*.
Refer to 6:29:1:2.