Leviticus 6:13

The fire shall ever be burning. — This fire, which first came down from heaven (Leviticus 9:24), was to be continually fed with the fuel especially provided by the congregation, and with the daily burnt offerings. During the second Temple, this perpetual fire consisted of three parts or separate piles of wood on the same altar: on the largest one the daily sacrifice was burnt; the second, which was called the pile of incense, supplied the fire for the censers to burn the morning and evening incense; and the third was the perpetual fire from which the other two portions were fed. It never was quenched till the destruction of the Temple by Nebuchadnezzar. Indeed, we are positively assured that the pious priests who were carried captives into Persia concealed it in a pit, where it remained till the time of Nehemiah, when it was restored to the altar (2Ma. 1:19-22). The authorities in the time of Christ, however, assure us that the perpetual fire was one of the five things wanting in the second Temple.