en_tn_lite_do_not_use/1sa/17/10.md

I challenge the ranks of Israel

"I challenge the army of Israel"

all Israel

This refers to the Israelite soldiers who were there.

they were discouraged and greatly afraid

The words "discouraged" and "greatly afraid" mean basically the same thing and emphasize the intensity of their fear. (See: rc://en/ta/man/translate/figs-doublet)