Verses with the word firebrand in the Old Testament (2 verses):

Judges 15:4
And Samson went and caught three hundred foxes, and took firebrands, and turned tail to tail, and put a firebrand in the midst between two tails.

Amos 4:11
I have overthrown some of you, as God overthrew Sodom and Gomorrah, and ye were as a firebrand plucked out of the burning: yet have ye not returned unto me, saith the LORD.