Why should they offer Korbanos?
'Rashi': It is in order to be pleasing to Me. It is on condition that Iyov will pray for you.
Malbim: They should offer Olos, to atone for thoughts of the heart 1 . Their hearts doubted basic tenets of Emunah, unlike their mouths.
According to the opinions that Iyov lived after the Churban, how could they offer Korbanos? Once the Mikdash was built, Bamos were forbidden permanently!
Refer to 1:5:8:1.
If Iyov returned with Olei Bavel, they offered in Bayis Sheni. If he was in Yemei Achashverosh, perhaps they offered in Bayis Rishon; more than 60 years later, when they sought beautiful girls, Iyov's were the most beautiful. (PF)
This was a Hora'as Sha'ah 1 ; Hashem commanded them. (PF)
This is always for a special need. Perhaps Hashem needed to teach how severe their sin was! Do not say that they were Goyim. All the opinions that Iyov lived after Moshe hold that he was Jewish, for Hashem granted Moshe's request not to give prophecy to Goyim (Bava Basra 15b)! (PF)
Why must Iyov pray for them?
Ibn Ezra, Malbim: They condemned him improperly. It was clarified that he is a total Tzadik!
Why did he say "Ki Im Panav Esa"?
'Rashi': I will favor him to accept his Tefilah. Here, "Im" is like Asher, like "Ad Im Kilu Lishtos", "Im Kofer Yushas Alav."
Ibn Ezra: Hashem favors Tzadikim in this world, but not in the world to come. Since Iyov's friends justified Hashem, if He would bring evil on them, errant people would say that this is depraved.
