What did Hashem do for 40 years?
Rashi: He killed Dor ha'Midbar.
Radak: He decreed that they will remain in the Midbar for 40 years [before entering Eretz Yisrael], and quarreled with them [Malbim - all 40 years].
What is the meaning of "Akut"?
Rashi: I quarreled and fought with them. This is like "Naktah Nafshi b'Chayai" (Iyov 10:1) [Radak - and "Ra'isi Bogedim va'Eskotetah" (119:158)].
What is "To'ei Levav"?
Radak: Their hearts are for evil; they do not believe in Me.
Malbim: They did not have "Lev Lada'as v'Einayim Lir'os" (Devarim 29:3).
What is the meaning of "Lo Yad'u Derachai"?
Radak: They did not recognize all the miracles that I did with them, and they feared to enter the land, and they did not trust in Me. Therefore, I swore that they will not come there.