Why did he say "Zach v'Yashar"?
Devar Eliyahu: Zach is in the heart, and Yashar is in deed.
What do we learn from "v'Shilem Nevas Tzidkecha"?
Rashi: [If you are clean and straight,] He will make the dwelling of your virtue complete.
Ibn Ezra #1: Tzidkecha is the Neshamah. V'Shilem is like Shalom (its dwelling will be peaceful).
Ibn Ezra #2: V'Shilem is from Tashlum (payment); it is as if it says bi'Nevas Tzidkecha (the payment will be in the dwelling of your Neshamah).
Devar Eliyahu #1: Until sins are cleansed, merits are not aroused. Now, in this world, they will be aroused for you, and you will receive full reward in the world to come. Here, one eats only the Peros of his Mitzvos - "Ki Fri Ma'aleleihem Yochelu."
Devar Eliyahu #2: He will complete his days and years, and not lack anything from them - "Zaken Ba ba'Yamim."
Devar Eliyahu #3: An Aveirah will not extinguish a Mitzvah. His Mitzvos and virtue will be complete.
Malbim (3): You think that Hashem removed His Hashgachah from you. No! Refer to 8:7:1:4.
