What is the grammatical form of "Hafach"?
Radak #1: It is Po'el Yotzei (it acts on others); Hashem switched their hearts, for He decreed "va'Avadum v'Inu Osam" (Bereishis 15:13).
Radak #2: It is Po'el Omed (the action applies only to the subject). It is as if it says "Nehfach Libam" (their hearts switched).
Why did they hate them?
Malbim: (a) Due to [the size of] the Am - "Havah Nischachmah Lo Pen Yirbeh" (Shemos 1:10). (b) Yisrael serve Hashem; the Egyptians wanted to uproot them from serving Hashem. This is why it says "Lehisnakel ba'Avadav."
What is "Lehisnakel"?
Radak: It is to think bad thoughts, how Yechalu (they will eradicate) them - "Havah Nischachmah Lo" (Shemos 1:10).
