Psalms 55:10 Commentary: Rashi

divide their tongue Divide it so that no one should pay them heed. And Menachem (p. 142) interpreted פלג as an expression of division.

Destroy (Defey or defay in Old French, destroy, defais in modern French,) like (Lam. 2:8): “He did not restrain his hand from destroying (מבלע).” So did Menachem interpret it [p. 46].

for I have seen violence and strife in the city through them.