Rashi on Isaiah
all day This is the interrogative. Therefore, it is voweled with a hataf pattah.
Ibn Ezra on Isaiah
Doth the plowman, etc. The plowman tills the ground once and twice, and sows, then the earth by its natural power brings forth the increase.
Rashi on Isaiah
shall...plow One who plows to sow - does the one who plows to sow plow forever? If so, what does he accomplish? Similarly, the prophets admonish you to bring you back to do good deeds. Shall they admonish forever and not accomplish?