In the Beracha of Retzei, the third to last Beracha in the Amida, we beseech God, "and the fires of Israel and their prayers, may You speedily and lovingly accept, willfully" ("Ve'ishei Yisrael U'tefilatam Meheira Be'ahava Tekabel Be'ratzon"). The question was asked, why do we ask God to accept "the fires of Israel," meaning, our sacrificial offerings, if we do not offer sacrifices due to the absence of the Beit Ha'mikdash?
The Mishna Berura (120:1) cites three different interpretations that have been suggested to resolve this question:
1) The Tur explains this passage as a reference to our prayers, which are recited in lieu of the sacrifices. When we ask the Almighty to accept "the fires of Israel," we in fact ask that He accept our prayers which take the place of sacrifices in the Temple's absence.
2) The Midrash tells that Michael, one of the heavenly angels, occasionally "sacrifices" the souls of the Tzadikim before God in the heavens. He brings these righteous souls to God in the hope of invoking their merit on behalf of the Jewish people. Accordingly, when we ask God to accept "the fires of Israel," we refer to these "sacrifices" offered by the angel Michael in the heavens.
3) Finally, some Rabbis understood the phrase "the fires of Israel" as a continuation of the previous clause: "and restore the service to the Sanctuary of Your abode" ("Ve'hashev Et Ha'avoda Li'dvir Beitecha"). According to this view, we should read this passage as follows: "and restore the service to the Sanctuary of Your abode, as well as the fires of Israel" ("Ve'hashev Et Ha'avoda Li'dvir Beitecha Ve'ishei Yisrael"). Thus, we do not, in fact, ask that God accept "the fires of Israel," but rather pray that He restore the sacrificial service through the rebuilding of the Beit Ha'mikdash.
This discussion should remind us to ensure to follow the precise, traditional text of our prayers even if at first it seems difficult to understand. This passage in "Retzei" demonstrates how even seemingly ambiguous or inscrutable texts of our prayer service can be convincingly explained. It therefore behooves us to carefully recite the precise text of our Tefilot as it has been transmitted to us through tradition, even those texts that at first appear difficult to explain.