Why did he say "Gam"?
Rashi: Is it not enough that He created us?! Will we receive also the good, but not the bad?!
Devar Eliyahu: Tzadikim do not consume the reward of their good deeds in this world, only their fruits. He asked, do you want to consume also the fruits and the principal [in this world], but not the bad?!
Malbim: Iyov thought that bad must be mixed with good. Also, there is more bad in the world than good. If one wants to drink much wine or eat much honey, he should not complain if he gets drunk or his stomach is harmed. He sinned in his heart. He thought that Hashem created the world to be bad for man! This is the source of all the bitter words he said below.
What do we learn from "b'Chol Zos? bi'Sfasav"?
Rashi (from Bava Basra 16a): He did not sin in his words, but he sinned in his heart. Malbim - refer to 2:10:1:3.
Ibn Ezra: Later he will sin with his lips, and say words amidst his great pain.
