What is the meaning of "Yagiruhu Al Yedei Cherev?
Rashi: Enemies should come upon my pursuers and kill each via the sword. The verse is abbreviated; it omits who will kill them. Yagiruhu is an expression of Greirah (dragging) - "Megurim b'Morad" (Michah 1:4).
Radak: The Megirim should make Sha'ul fall. Hagarah is spilling, like "vecha'Mayim ha'Nigarim" (Shmuel II, 14:14), "Eini Nigrah" (Eichah 3:49). It is used regarding killing, for the sword makes the blood spill. It is also used for dry things that roll from a height to a depth - "v'Higarti la'Gai Avaneha" (Michah 1:6).
Malbim: Even if Sha'ul and his men will, via their swords, expel David from the caves where he hides, and he will need to go to other lands, and the caves will be foxes' habitations [David will rejoice in Hashem - verse 12].
What is "Menas Shu'alim"?
Radak: The other haters with Sha'ul should be the portion of foxes, which eat dead bodies. The sword will kill them, and foxes and Chayos will eat them.
Malbim: Refer to 63:11:1:3.
