What is the question "ha'Yelechu Shenayim Yachdav"?
Rashi: You tell the Nevi'im not to prophesize. Do they prophesize from their hearts, if they were not commanded?! Everything is done only via them!
Radak: After you sinned against Me, see what happened to you! One cannot leave the city due to fear of the enemy, and not even two, unless they coordinated to go together and stand against the enemy if the enemy will encounter them.
Radak citing Ibn Ezra: This refers to above. You commanded the Nevi'im not to prophesize (2:12). Before I punish you, I will inform you via the Nevi'im ? perhaps you will repent. Had I not revealed to the Navi to rebuke you, he would not prophesize from his heart ? how would he know what I will do?! His words are not chance. Is it possible for two people to go to one place at one moment, for one reason, if they did not coordinate this?! When you see that the Navi's words are Emes, know that I sent him. How can he rebel against My mouth and not prophesize, like you tell him?!
Malbim: From here until verse 8 is an introduction to the Nevu'os from verse 9 until the end of Perek 4. (a) Know that punishments are not chance, rather, Hashgachah. Do two people go together if they did not coordinate this? Two different people will not go together on the same path for the same reason, unless they coordinated this; it is not chance. Since several nations joined to fight Yisrael (verses 9-11), it is not chance. Hashem summonsed them to this; His Ru'ach gathered them.
What is the meaning of "Bilti Im No'adu"?
Rashi: Unless they fixed a time to go together to a particular place.
Refer to 3:3:1:2-4.
