en_tn/isa/05/26.md

He will lift up a signal flag for far away nations and will whistle for those at the end of the earth

Isaiah says the same thing in two different ways. God causing the armies of nations that are far away from Judah to come and attack is spoken of as if he would raise a flag and whistle to call them to Judah Alternate translation: "He will call for the armies of nations that are far away from Judah and tell them to come" (See: rc://en/ta/man/translate/figs-parallelism and rc://en/ta/man/translate/figs-metaphor)

whistle

a loud, high pitched noise a person makes with their mouth to call a person or animal that is far away

they will come

"the enemy army will come"

speedily and promptly

These words mean basically the same thing and emphasize how quickly they will come. Alternate translation: "very quickly" (See: rc://en/ta/man/translate/figs-doublet)