Why does it say "Ki Adam Le'amal Yulad"?
Sanhedrin 99b: Man was created to toil. Is this with his mouth, or in work? "Ki Achaf Alav Pihu" - it is with his mouth. Should he toil in Torah, or in Sichah 1 ? "Lo Yamush Sefer ha'Torah ha'Zeh mi'Picha" - in Torah.
Rashi: It is impossible that he will not sin, and receive Amal (punishment) for his sin.
Devar Eliyahu: There are two shortcomings in man's life. (a) It is short and bad. All his days are full of toil! Also refer to 5:7:2:5.
Malbim: Man was created to toil with his hands to produce his food. One who makes wealth without toil, this is sin - it will not last with him and his sons. This is unlike you said, that success is decreed.
Ben Yehoyada: Sichah is Tefilah. Should one toil to say every word, from the Akeidah until Aleinu, with great Kavanah, like the Ba'al Shem Tov and Chasidim? This will take many hours; little time will remain for Torah. Or, should one pray at a moderate pace, and much time will remain for Torah, like the Gra and the Misnagdim?
What do we learn from "u'Vnei Reshef Yagbihu Uf"?
Rashi: Man is not like angels and Ruchos - they elevate and fly. They are not lower beings, that the Satan and Yetzer ha'Ra can rule over them. Reshef is like "Rishfei Kashes." A flying arrow is called Rishfei, an expression of flying.
Ibn Ezra: Some say, just like the nature of birds is to fly, the nature of man is to toil. This is like Lechumei Reshef, which refers to all birds.
Ibn Ezra: Some say, Bnei Reshef proper to be in Gehinom, will rise in this world 1 .
Ibn Ezra: Some say that Bnei Reshef are sparks of fire. Man always sees sunrise and sunset; it is not wondrous 2 in his eyes. Rain comes only sometimes; sometimes it is withheld, and people need to pray for it. Therefore, it says "ha'Nosen Matar" after "Ose Gedolos" (9-10).
Devar Eliyahu: The other shortcoming in man's life is that it ends suddenly, without prior notice. Bnei Reshef are sparks that come from burning coals. Once these coals rise, they extinguish immediately. So man's life rises, and his Ner (Neshamah) extinguishes suddenly.
Malbim: You say that angels send sparks and influences below on all of man's actions. No! "U'Vnei Reshef Yagbihu Uf" - they are in the upper world; they cannot influence good or bad on the lower world.
