Responsum: On the Babylonian Talmud, Tractate Megillah

Abaye said: These [i.e., the curses in Leviticus (26:14–46)] are said in the plural and Moses recited them from the mouth of the Almighty, whereas these [i.e., the curses in Deuteronomy (28:15–69)] are said in the singular, and Moses recited them from his own mouth. [b. Megillah 31b]

You should know that the entire Torah, from In the beginning (Genesis 1:1) to In the sight of all Israel (Deuteronomy 34:12) existed in written form before the Holy One, two thousand years prior to the creation of the world, as we have said in several places. Do not suggest that the commandments that were stated to Moses before the . . . [were not] written down two thousand years prior to the creation of the world, such as the Ten Commandments, circumcision, eating the paschal lamb, and those commandments that [Moses] asked about and which were subsequently stated to him. [ . . . ] You must thus say that there were 613 commandments [from the start]. [Nor should you claim that] the genealogies were not written down. That is not the case; in fact, all the genealogies, such as: And the sons of Ham: Cush, Mizraim, Put, and Canaan (Genesis 10:6)—despite the fact that no person was yet created who could have given birth to Ham [ . . . ], and all the more so [the genealogies of Israel], they were all written down before He-who-spoke-and-the-world-was-created. [ . . . ]

It is a well-known and clear fact, not subject to dispute, that the Torah, which the Holy One gave to Israel at Mount Sinai, was written down by Moses [as dictated to him directly] from the mouth of the Holy One. Its content was stated to him by the Holy One. [He told him to write every word,] that every full word should be full [i.e., He specified the vowels], and he would read out each letter that He instructed him to write and then he would write it down, he would read it and write it. [ . . . ] It is for this reason [that, if the letters and words in a Torah scroll] differ, for example if there was a difference in the tags [the “crowns” or ornaments on the letters] or in which letters were full or deficient, or the open and closed paragraphs, such Torah scrolls must be buried.

And likewise, there are cases where the Holy One instructed Moses to write . . . in the style of the Holy One, speaking to [Moses] without an intermediary, such as: I am the Lord your God, who brought you out [of the land of Egypt] (Exodus 20:2) and the curses of the Book of Leviticus, in which it is written: [ . . . ] Then I will walk with you (Leviticus 26:28); And I will appoint over you (Leviticus 26:16); And I will bring upon you (Leviticus 26:25). Likewise, there are statements that the Holy One issued to Moses, such as When you come (Numbers 34:2), where He was telling Moses what He would do with Israel. [ . . . ] At the same time, there are statements that the Holy One told Moses to write down as though he [Moses] himself had said them to Israel, such as Hear, O Israel, etc. (Deuteronomy 6:4) and For the Lord your God, He is God of gods, etc. (Deuteronomy 10:17). The same applies to the curses in the Book of Deuteronomy, e.g.: The Lord will smite you (Deuteronomy 28:22), and The Lord will bring a nation against you (Deuteronomy 28:49), and The Lord shall scatter you (Deuteronomy 28:64). This is the meaning of Abaye’s statement that these are stated in the plural and that they were spoken to him by the Holy One.