1)
What does "Yesharim Yishkenu Aretz" refer to?
1.
Rashi: It refers to the world to come.
2.
Malbim: Yesharim's nature is straight, both regarding Binah and Midos. Automatically they go in the straight path.
2)
Why does it say "u'Smimim Yivasru Vah"?
1.
Rashi: This will be when the Resha'im go to Gehinom.
2.
Malbim: Temimim are those whose deeds are fixed, and never change, in good or bad times. They do everything l'Shem Hashem, without any other motivation. Yesharim could do bad occasionally, and they would not remain forever in the land. Temimim will remain in it; they will never falter from their virtue.
