What was annulled, and on what day?
Radak: The Bris was annulled on the day that Yoshiyah died, for the nations ruled over the three shepherds (his sons, who reigned after him).
Refer to 11:10:1:3.
Malbim: The Bris was annulled when the Yevanim overpowered Paras. Even though they renewed the Bris with the Yevanim in the days of the Chashmona'im, and later with the Romiyim in the days of Hordus, the Bris was annulled on that day. From then there was not a fixed Bris; it was constantly annulled.
Who will know?
Rashi: The Tzadikim among them, who guard My Chukim.
Radak: The Tzadikim among them, who guard what I said via the Nevi'im. [Most Jews] did not heed them, for they did not believe them, but the good ones guarded Me (My word). "Ha'Shomerim" is like "v'Aviv Shamar Es ha'Davar" (Bereishis 37:11).
Malbim: Chachamim and people with Ru'ach ha'Kodesh who guarded Mishmeres Hashem.
What do we learn from "Ki Devar Hashem Hu"?
Rashi: Hashem already told us this decree via Moshe ? "Yolich Hashem Osecha v'Es Malkecha" (Devarim 28:36).
Radak: When the punishments come, they will know that [the Nevi'im's words] were Devar Hashem.
Malbim: They recognized that [annulment of the Bris] was Devar Hashem. Yechezkel and Zecharyah already prophesized about it, and Daniel saw the four kingdoms (that will pain Yisrael.
