At one point in the Rosh Hashanah prayers, we recite the section of "Hayom Te’amesenu," a series of expressions of our hopes for a favorable judgment on this day of Rosh Hashanah. After each pronouncement, we recite "Amen."
In one version of this section, which appears in some Mahzorim, the text includes the passage, "Hayom Tichtebenu Be’rahamecha Le’haim Tobim U’le’shalom" ("Today You shall inscribe us in Your compassion for good life and peace"). However, the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in Parashat Nisavim (21), ruled that the word "Hayom" ("today") should be omitted from this passage. The Gemara teaches that only the "Sadikim Gemurim" – completely righteous – are inscribed for a good year immediately on Rosh Hashanah; for everyone else, the judgment is finalized only later. It is inappropriate and arrogant to ask to be inscribed on Rosh Hashanah along with the righteous Sadikim, and so we should simply request, "Tichtebenu Be’rahamecha Le’haim Tobim U’le’shalom" – that we should be inscribed for a good life, without asking that this judgment should be written already on Rosh Hashanah.
One must ensure to add the word "Be’rahamecha" ("in Your compassion") in this passage, in order to make a separation between the words "Tichtebenu Le’haim Tobim U’le’shalom." The first letters of these words ("Tav," "Lamed," "Tet," "Vav") can be rearranged to spell the word "Talot," which means "curse." On Rosh Hashanah, we endeavor to avoid any inauspicious omens for the coming year, and so we add the word "Be’rahamecha" to avoid an allusion to the ominous word "Talot."
Summary: In the "Hayom Te’amesenu" section of the Rosh Hashanah prayer service, some Mahzorim include the passage, "Hayom Tichtebenu Be’rahamecha Le’haim Tobim U’le’shalom," but it is more correct to omit the word "Hayom," and recite, "Tichtebenu Be’rahamecha Le’haim Tobim U’le’shalom."