Radak: Usually, the Makor (infinitive) precedes the [conjugated] verb; when the Makor follows the verb, it is to strengthen the action, like "va'Yvarech Baruch Eschem" (Yehoshua 24:10).

Malbim: The verse shows their Sheker, how they enticed everyone differently. To those who believe in Nevu'ah from Hashem, just they vex and disgrace Hashem and do not heed His rebuke, they say that Hashem promised Shalom. To those who deny Nevu'ah from Hashem, and go in the freedom of their hearts (heresy), they say that what the Nevi'im say in the name of Hashem that evil will come, it is Sheker, for Hashem cannot speak with man; man cannot know His secrets (verse 18).

Rashi: It means ul'Chol Holech bi'Shrirus Libo (to everyone who does whatever he desires, they say