מדרש על ישעיהו 34:10

Observe how precious the altar of brass that Moses constructed was to the Holy One. The Holy One, blessed be He, said: Because of this altar upon which fire will burn day and night, I will call to account the kingdom of Edom through fire, and she shall burn day and night, as is said: It shall go up forever; from generation to generation it shall lie waste. None shall pass through it forever and ever (Isa. 34:10).