1)
What is "Maras Nafsho"?
1.
Rashi: It is what he toiled in Torah. Therefore, "uv'Simchaso Lo Yis'arev Zar" when he receives his reward in the future.
2.
Rashi (12): Yisrael were bitter in Galus, and were killed for Kidush Hashem. No stranger will share in their future Simchah!
3.
Malbim: Hidden in the clefts of the heart of an Evvil, his inner Nefesh is bitter and has no rest, for he knows that he deserves punishment for his deeds.
2)
Why does it say "uv'Simchaho Lo Yis'arev Zar"?
1.
Rashi: Refer to 14:10:1:1-2.
2.
Malbim: The Simchah of a Yashar's heart is very hidden; no one else knows it.
