What are the connotations of "u'Meshalem le'Son'av el Panav"?
Hadar Zekenim: He immediately pays the Rasha in the world according to his evil deeds, and makes him perish from this world. It says "Shuvu
Seforno: 'Rasha ve'Tov lo' - either because Hashem does not withhold the reward of any creature or on account of Z'chus Avos.
See Sifsei Chachamim.
Ramban: Just as He punished the Egyptians. When a Rasha lives long, it is due to the Midah of "Shomer ha'Chesed" (in the previous Pasuk - inasmuch as Hashem is rewarding him in his lifetime for a good deed that he performed (See Ramban, DH 'veha'Midah ha'Zos'). Citing Koheles Rabah, the Ramban ascribes the longevity of a Rasha to one of three reasons: a. He might do Teshuvah; b. As a reward for a Mitzvah that he performed; c. Perhaps Tzadikim will descend from him. We find that Chizkiyah came from King Achaz, Yoshiyah from King Amon, and Mordechai from Shim'i ben Gera.
What does "ha'Yom La'asosam" imply?
Avodah Zarah 3a: Today (in this world) is the time to do Mitzvos, and not tomorrow (in the world to come). Today is the time to do Mitzvos, but it is not the time to receive their reward.
Why does it repeat "l'Son'o El Panav Yeshalem Lo"?
Hadar Zekenim, Rosh: We do not expound the repetition.
Moshav Zekenim #1: It says in Kidushin 39b that if one's sins outweigh his merits, He will be rewarded for his Mitzvos in this world, and lose the world to come. The Reisha of our verse teaches this. The Seifa discusses a Tzadik [with a minority of Aveiros]. Hashem appears to act towards him in this world like a Sonei; He punishes him for all his sins in this world, so he will merit the world to come. Therefore, the Seifa does not say "Leha'avido".
Moshav Zekenim #2: The entire verse discusses a Rasha. The Reisha teaches that he is rewarded for his Mitzvos in this world, and loses the world to come. The Seifa teaches that Hashem pays him immediately; He does not wait until the end of his life.
QUESTIONS ON RASHI
Rashi writes that Hashem pays the Rasha in his lifetime in order to make him lose the world to come. This encourages Resha'im - they will be serene in this world, and they are not concerned for what will be after!
So it says in Kidushin 39b - if one's sins outweigh his merits, Hashem will do good to him. He will be rewarded like (is proper for) one who fulfilled every letter of the Torah! 1
Rashi writes that Hashem pays the Rasha in his lifetime in order to make him lose the world to come. This seems unfair (the world to come is worth far more than any reward in this world)!
Michtav me'Eliyahu (5, p.445): Mitzvos of a Rasha are merely a Kli for Ruchniyus, therefore their reward is in the framework of a Kli - in this world. Mitzvos of a Tzadik are a spiritual entity, therefore their reward is in the world to come.