Why does it say "Niru Lachem Nir"?
Rashi: Farmers plow in summer to kill grass roots, lest they sprout thorns at the time of seeding in winter. Also you should improve your ways before the evil comes, lest your prayer be despised when you scream!
Radak: Niru is like Haniru, like Simu - Hasimu. The Hei of the conjugation is omitted, for ease of pronunciation. Nir is plowing before seeding. This plowing uproots thorns and weeds; afterwards, it is proper for seeding. This is a parable; improve your hearts to understand Hashem's words, and accept them in a proper heart. This is like one who plows the field to accept seeds. Do not say with your mouths 'we will heed Devar Hashem', and your heart is not proper with Him - "Lo Shavah Elai
Why does it say "v'Al Tizre'u El Kotzim"?
Rashi: Your screaming to Me should not be amidst evil, rather, amidst Teshuvah. Do not be like one who seeds without plowing; it is transformed to thorns.
Radak: This is like Al Kotzim. "va'Yach ha'Pelishti El Mitzcho" (Shmuel I, 17:49) is like Al Mitzcho, and similar verses.
