(Isa. 8:9)
The repetition of phrases at the end of verse 9 accentuates the message and provides a form of the comparative. The comparative degree in Hebrew was formed by simply repeating a word or phrase. To repeat the item three or more times made it superlative. Whereas in English one would say “good,” “better,” and “best” to indicate comparative degrees, in Hebrew one could say “good,” “good, good,” and “good, good, good.” Thus, in the verse above, Isaiah is warning the nations that if they prepare for battle, they will be devastated.
(Victor L. Ludlow, Isaiah: Prophet, Seer, and Poet [Salt Lake City: Deseret Book Co., 1982], 148.)