Why does it say "Al Gabi Charshu"?
Radak: It is a metaphor for the great suffering, harsh work and disgrace - "va'Tasimi cha'Aretz Gevech vecha'Chutz la'Overim" (Yeshayah 51:23).
Malbim: "They could not overcome me" (verse 2) - this was not due to my strength. Just the contrary, I was not like a city fortified against the enemy, rather, like a plain that the enemy goes on it as it wants.
What is "Ma'anisam"?
Rashi: It is the plow furrow - "keva'Chetzi Ma'anah Tzemed Sadeh" (Shmuel I, 14:14) is [half] the length of a furrow that yoked oxen 1 plow in a field (Rashi there).
Radak there: It is as if it says Tzemed Bakar ba'Sadeh.
Why does it say "He'erichu Ma'anisam"?
Radak: One plows in a line as long as he wants, and then another furrow the same length, and so on, until he plows the entire field. The longer the furrow, the cattle must exert more until they rest at its. They made their furrow long - they did not let us rest from their work and burdens.
Malbim: They lengthened the furrow as they wanted, for no hill stopped them. Based on nature, they would have trampled [Yisrael].
