Why does it say that Ashur will not save us?
Rashi: They will say also this - we will no longer seek help from people, not from Ashur and not from Egypt.
Radak: Confess in front of Him, and say that Ashur, in which we trusted until now, will not save us. There is no power to save us other than You - salvation is Hashem's!
Malbim: Malchei Yisrael relied on them when they had difficulty.
Why will we not ride on a horse?
Rashi: This was the help from Egypt - they sent horses, like it says "Lo Chi Al Sus Nanus... v'Al Kal Nirkav" (Yeshayah 30:16).
Radak: We used to send people riding on horses to Ashur to save us; we will not do so any more.
Malbim: Egypt used to give horses and riders, to fight with their strength.
What did they used to say about their handiwork?
Rashi: That they 1 are our gods.
Malbim says that they will not say so about idols and the Ma'arachah. I do not see a hint to the Ma'arachah in our verse. (PF):
What is the meaning of "Asher Becha Yerucham Yasom"?
Rashi: Our hope is only in You - You have mercy on orphans.
Radak: One who has no strength, You give to him strength and save him. So You will do to us!
Malbim: One who has no helper based on nature, You have mercy on him. Since we have no trust and hope in anything other than You, Your mercy will be on us!