What is the meaning of "Maru"?
Rashi: They angered Him. This is like "Mamrim Heyisem Im Hashem" (Devarim 9:7).
Radak: It is rebellion, like "Merisem Pi" (Bamidbar 27:4). After He redeemed them from the affliction, they rebelled against His word and did not heed His voice and Ru'ach Kodsho.
Malbim: They switched (did unlike) His Mitzvos.
What is "Ru'ach Kodsho"?
Radak citing Targum Yonasan: It is the Nevi'im's words said with Ru'ach ha'Kodesh.
What is "Itzevu"?
Radak: This is vexing, like "Kamah Yamruhu va'Midbar Ya'atzivuhu" (Tehilim 78:40).
Malbim: The verse depicts that they saddened Ru'ach Kodsho via causing Him to punish them for their rebellion, like a father is pained when he strokes his beloved son.
How did Hashem reverse to be an enemy?
Radak: As opposed to redeeming them from an enemy, He fought them, and all their matters came in an evil way, until they said 'this is from Elokim.'
Malbim: Initially, He was pained due to their pain. Afterwards, He was like an enemy who rejoices over their evil - "v'Hayah Ka'asher Sas Hashem Aleichem Leheitiv Eschem Ken Yasis 1 Hashem Aleichem Leha'avid Eschem" (Devarim 28:63)
Megilah 10b: Hashem does not rejoice over punishing Resha'im; He makes others rejoice over this. It says "Yasis", and not 'Yasos'. (Why does Malbim explain unlike this? - PF)
Why does it say "Nilcham Bam"?
Malbim: Afterwards, not only did He abandon them to the enemy and rejoice over their plight. He actively fought and harmed them. Their punishment was not natural, rather, via Hashgachah - "Ki Tzuram Mecharam va'Shem Hisgiram" (Devarim 32:30).
