When will Hashem come close?
Radak: On the day mentioned.
Malbim: You want Hashem to be found among people in this world to judge the Tzadik and Rasha, and to pay their reward and punishment immediately. This cannot be until the future, when the time of Tikun will come. Then there will be no impurity or light sin, for Hashem will judge with fire. This world is the world of choice and test. It cannot conduct like you want. For idolaters, the world conducts naturally, and some succeed until the Ketz. However, for Yisrael, I will bring judgment close (soon). It will not be like in the future, when even light sins will be purified. It will be only for severe sins - witches, adulterers...
To whom does "Aleichem" refer?
Radak: To the generation in that time. The generations that passed and did not receive their judgment in this world, will receive it in the world to come.
Why will Hashem be the witness?
Radak: He knows hidden matters, and will testify about what they did.
What will Hashem rush to do?
Radak: He will pay their recompense.
Malbim: I will judge them before the future time of judgment, for I cannot abandon punishing them until their measure is full, for then they would be totally eradicated.
What is the meaning of "u'Matei Ger"?
Radak: They tilt the judgment of a convert.
