1)
How is he considered like one who descends to the pit?
1.
Radak: in Galus, I have no strength to be saved from those who harm me.
2.
Malbim: He depicts himself like one who faints, and people err and think that he died, and they bury him. He is still alive, and feels, just he has no strength to move a limb to show that he is alive. People considered me like one who should descend; they wanted to bury me.
2)
What is the meaning of "Ein Eyal"?
1.
Rashi: He has no strength. This is like "Eyalusi l'Ezrasi Chushah" (22:20).
