en_tn_condensed/mat/13/42.md

furnace of fire

This is a metaphor for the fires of hell. If the term "furnace" is not known, "oven" can be used. Alternate translation: "fiery furnace" (See: rc://en/ta/man/jit/figs-metaphor)

weeping and grinding of teeth

"Grinding of teeth" here is a symbolic act, representing extreme sadness and suffering. See how you translated this in Matthew 8:12. Alternate translation: "weeping and showing that they are suffering very much" (See: rc://en/ta/man/jit/translate-symaction)