What are "Divrei ha'Bris ha'Zos"?
Radak (1): They are what is written in the Torah, Brachos and curses - Im Tishme'u
Regarding the Brachos and Klalos in Devarim, it says "Im Shamo'a Tishma
Why did Hashem mention the Bris?
Radak: Bris is a lasting [agreement] between man and his friend; if they make stipulations between themselves, they make a Bris to fulfill the stipulations. All the more so between Hashem and people, it is proper to fulfill the Bris!
Why does it say "v'Dibartem" (plural)?
Radak: You and the other true Nevi'im. Tzefanyah prophesized in the days of Yoshiyah, and perhaps there were also others.
Targum Yonasan: You (singular) will speak them (Divrei ha'Bris). Radak - it seems that his text said v'Dibartam with a Kamatz under the Tov. In our text, there is a Segul under it.
Malbim: First it says "Shim'u"; remind them, that they should hear by themselves amidst love. After, you and those who heard amidst love should say to the rest of the Am, and scare them with the punishment for one who does not heed.
Why does it say "El Ish Yehudah"?
Radak: They are all in a Klal, like one. Verses use the singular for a Klal, e.g. "va'Yhi Li Shor v'Chamor" (Bereishis 32:6), "v'Ish Yisrael Nigash" (Shmuel I, 14:24) and many like this.
Why does it say "v'Al Yoshvei Yerushalayim"?
Radak: This is like v'El Yoshvei Yerushalayim. Also "va'Yelech Elkanah ha'Ramasah Al Beiso" (Shmuel I, 2:11) is like El Beiso. "Va'Tispalel Al Hashem" (ibid., 1:10) is like El Hashem, and similar verses.
