5:22 What is the meaning of "Halmu Ikvei Sus"?
Rashi: The horses' hooves came off 1 , because the star heated the mud; when one cooks feet, the hooves fall off. Due to this, the horses' feet were stricken (Mechilta Beshalach 5).
Radak: The hooves came off because they were running so much in the war.
Malbim: Refer to 5:22:2:3.
Ba'al ha'Turim (15): It says here va'Yaham, just like at Keri'as Yam Suf.
What is the meaning of "mi'Daharos Daharos Abirav"?
Rashi: They made the horses dance in war. This is like "Sus Doher" (Nachum 3:2).
Radak: Dehirah is a horse banging its feet strongly on the ground, whether when running or not when running; the latter looks like dancing. Abirav refers to the horsemen, or the horses.
Malbim: The waves of the river were like mighty [warriors] making their horses dance, to greet Sisera's chariots and horses. These waves removed the horses' hooves.