Why did He say "Al Kol Asher Eshlachacha"?
Radak: Al is like El, e.g. "va'Yelech Elkanah ha'Ramasah Al Beiso" (Shmuel I, 2:11) is like El Beiso.
Malbim: You said that a youth is not bold to approach elders [to rebuke them]. I send you. A Shali'ach of a great king is not ashamed to go wherever he is sent, for he knows the level of the one who sent him, even if he himself is young and disgraced.
Why did He say "Telech"?
Radak: Yirmeyah was in Anasos, and Hashem wanted to send him to Yerushalayim, to rebuke the king and His nation.
Why did He say "Eshlachacha" and "Atzavecha"?
Rashi: These refer to being sent to other nations and Yisrael, respectively.
Why did He say "Asher Atzavecha Tedaber"?
Radak: I will fix the words in your mouth. You will know to speak rebuke without fear.
Malbim: You said that you do not know how to arrange your words. You need to say only what I will command you. I will put My words in your mouth!
