Since when reciting the Amida one must see himself as standing before the King, during the Ten Days of Repentance he must make mention of God’s kingship, which is manifest during these days when He judges His world. If one does not make mention of this, it is as though he is paying mere lip-service to God’s kingship, which is revealed during the Ten Days of Repentance. Accordingly, the Sages changed the conclusion of the third berakha of the Amida from the usual “ha-Kel ha-kadosh” (“the holy God”) to “ha-Melekh ha-kadosh” (“the holy King”). Additionally, the berakha of Hashiva Shofteinu (“Restore our Judges”) ends with “ha-Melekh ha-mishpat” (“the King of justice”) instead of “Melekh ohev tzedaka u-mishpat” (“King Who loves righteousness and justice”).
If someone accidentally concluded the third berakha with “ha-Kel ha-kadosh,” and did not realize his mistake almost immediately (tokh kedei dibur, i.e., within the time it takes to say “Shalom alekha rabbi”), he must begin the Amida again, because the first three berakhot are considered one unit, and one who erred in any of the three must return to the beginning of the Amida. If after finishing the Amida one is uncertain about whether he said “ha-Kel ha-kadosh” or “ha-Melekh ha-kadosh,” he should assume that he said “ha-Kel ha-kadosh” out of habit and must repeat the Amida. However, if he remembers thinking just before reciting the berakha that he must say “ha-Melekh ha-kadosh,” or if he remembers that he inserted “Mi khamokha” (see below), he can assume that he recited “ha-Melekh ha-kadosh,” and need not repeat the Amida (Taz 422:1; MB 582:4).
If one mistakenly concluded the berakha of Hashiva Shofteinu with “Melekh ohev tzedaka u-mishpat” instead of “ha-Melekh ha-mishpat” and did not correct it almost immediately, then according to some Sephardic poskim he has not fulfilled his obligation. Therefore, if he has not yet finished the Amida, he goes back to Hashiva Shofteinu, concludes it correctly, and continues with the Amida. If he has already finished the Amida, he must repeat it from the beginning, but he should stipulate that if he is not actually obligated to repeat it, his prayer should be considered voluntary (SA 118:1; Yeḥaveh Da’at 1:57). In contrast, according to Ashkenazic and some Sephardic poskim, even if he mistakenly concluded “Melekh ohev tzedaka u-mishpat,” he has fulfilled his obligation be-di’avad, since the word “Melekh” is mentioned in this formulation as well. Therefore, even if he did not quickly correct himself, he need not repeat the Amida (Rema 118:1; Ben Ish Ḥai, Nitzavim §19; Kaf Ha-ḥayim ad loc. 1). Since this is the majority custom, it is the appropriate ruling for one who is unsure of his family’s custom.
In addition to the above changes, there are four insertions in the Amida during the Ten Days of Repentance: “Zokhreinu le-ḥayim” in the first berakha, “Mi khamokha” in the second berakha, “U-khetov le-ḥayim” in the berakha of Modim, and “Be-sefer ḥayim” in the final berakha. One who forgot any or all of these additions need not repeat the Amida (SA 582:5).
During the Ten Days of Repentance we recite Avinu Malkeinu during Shaḥarit and Minḥa, as explained in section 6 below.