1)
Which Tzadikim see?
1.
Ibn Ezra: Noach and his children.
2)
Why do they rejoice?
1.
Malbim: They see, and understand that there must be another world in which will be reward and punishment. There will be judged [even] every hidden matter, good or bad. They will rejoice over their Avodah - via it, they are guaranteed that their Nefesh will remain in the eternal world of reward.
3)
Whom will a Naki mock?
1.
Malbim: Resha'im, for he knows that they will receive eternal punishment in the world of Neshamos.
