Eight-character idioms prone to fire

Jin Yu qi wai

Even the wise are not always free from mistakes.

A fool may gain something by worrying.

Snipers and mussels compete for the interests of fishermen.

There are trees and grass on Bagong Mountain.

It never rains but it pours.

Opportunity knocks but once.

Indigo is extracted from indigo plants, but it is bluer than the plants from which it comes.