Why does he not plow in winter?
Rashi: Due to the cold, the Atzel sits and does not do work, and does not engage in Torah. R. Yonah - do not say, 'when I will be free, I will learn' - perhaps you will not be free! (Avos 2:4)
R. Yonah: This comes to arouse people about the Midah of Zerizus. One should not slacken from work due to the cold or heat, and say 'when the time [of cold or heat] passes, I will resume work.' If he will do so, many times the work will cease when he slackens, and his loss will not be returned. E.g. if one refrains from plowing due to the cold of winter. Winter is the time to plow!
Malbim: The time for plowing is winter; then, it is cold. The Atzel does not like to work also at a proper time. All the more so he is lazy due to winter!
Why does it say "v'Sha'al ba'Katzir va'Ayin"?
R. Yonah: Because he refrained from plowing in winter, at the harvest time he has nothing [to harvest].
Orchos Tzadikim (Sha'ar ha'Atzlus DH v'Eizehu, citing Devarim Rabah 8:6): This is one who did not learn Torah in his youth, and he wants to learn in his old age, and he cannot.
Malbim: At the harvest time he wants to eat, and there is nothing. This is a Mashal for a man who is lazy and does not gather Chachmah in his youth. That is the time to plow the field of the Nefesh from thorns and images of desire, and to seed in it seed of Chachmah and Da'as. Then the hot passion of youth and its desires stop him, and he is lazy. In his old age, he has calmed from the heat of youth, but since he did not prepare the ground of the Nefesh for Chachmah in its time, he will not find fruits. Winter is a metaphor for the days of the Nefesh in the body. It is the time of plowing and seeding. When the Nefesh separates from the physical garment, that is the time of reaping. One who did not toil on Erev Shabbos, what will he eat on Shabbos?! (Avodah Zarah 3a)
