The answer to this question is not explicitly mentioned in the passage. In attempting to come to an understanding, it is important to recall the meaning of the burnt offering from Leviticus 1:1–17. The burnt offering was presented in order to make atonement and find acceptance before the presence of the Lord. By keeping the fire burning, the priests communicated that atonement was always available for the people of God. In other words, the perpetual fire signified that access to God was always ready and available.
2 Donne cet ordre à Aaron et à ses fils, et dis:Voici la loi de l'holocauste. L'holocauste restera sur le foyer de l'autel toute la nuit jusqu'au matin, et le feu brûlera sur l'autel.