What is the meaning of "Karov Matzdiki"?
Rashi: Hashem is close to me, to vindicate me in judgment.
Radak #1: Hashem is Matzdiki - He justifies my words and makes them Emes. He is close to me, and constantly gives to me new prophecies and repeats some, e.g. the matter of Sancheriv. Since He constantly repeats it, it will surely be fulfilled, and 1 they will not repent, to go after my words and regret the evil.
Radak #2: Soon Hashem will justify my words.
Malbim: I will be vindicated in my judgment.
This is like Kli Paz' text of Radak. Our text (it will be fulfilled if they do not repent) is difficult. This applies even to a Nevu'ah that was not repeated! (PF)
Why does it mention "Yariv" and "Mishpati"?
Malbim: Riv is in matters with claims and defenses. Mishpat is a clear matter. One who has a claim against his friend, they approach the judge, and he judges them. One who has Mishpat against his friend, he goes himself and demands what is owed to him.