Halakhah zu Könige II 25:34

And they are four days: The third day of Tishrei, on which Gedaliah ben Achikam was killed and the remaining coal of Israel was extinguished and this was a cause for the increase of the woes. The tenth of Tevet, on which the evil Nevuchadnetsar approached Jerusalem, as it is written in II Kings 25:1 and in Jeremiah 52:4, "in the ninth year of [the rule of Tsidkiyahu] on the tenth month on the tenth of the month, Nevuchadnetsar and all of his army came upon Jerusalem." And the Holy One, blessed be He, revealed this to Yechezkel - who was in Babylonia with the exile of Yochaniah - in a prophecy on that same day, as it is written (Ezekiel 24:1-2), "And the word of God was upon me in the ninth year on the tenth month on the tenth day, saying, 'Son of man, write for yourself the name of this day - of this very day - [as] the king of Babylonia approached Jerusalem on this very day.'" Which is to say that He commanded him to write the name of the day, which is the name of the month and also the specific day, and he wrote, "on the tenth of the tenth month," and the prophet did not know for what [reason] He commanded him to write this. And after he wrote it, He revealed to him, "You should know 'the king of Babylonia approached Jerusalem on this very day.'" And through this they all saw the true prophecy, as that day and that time were revealed to the prophet in Babylonia. Since, the exact [time] of the day is called "that very day," as per chatsot hayom (midday). And [this is] because there were then false prophets who fooled Israel, like Chananiah ben Azur and his colleagues, who prophesied that the Temple would not be destroyed and that Israel would not be exiled from their land, and [so] they strengthened the hands of the sinners. And Yirmiah - who rebuked them that they should return to God, and if not, the Temple would be destroyed and Israel would be exiled - they placed in the courtyard of the guardhouse and put him in a pit of mud, as is explained in Jeremiah 38. Hence, God informed Yechezkel the prophet in Babylonia that Yirmiah was a true prophet, and he prophesied in Babaylonia all that was happening in the Land of Israel, and that the Tenth of Tevet was the beginning of all the woes. Therefore, they established it as a fast day for the generations. And it is found in the name of the early ones, that if the Tenth of Tevet would come out on Shabbat, it would push off the Shabbat, as it is written about it, "on that very day," like Yom Kippur (Beit Yosef, Section 550 in the name of Abudarham). But we do not hold like this, as will be explained.

And on the seventeenth day of Tammuz, five things occurred. The tablets were broken. And the [daily] sacrifice in the first Temple ceased. And the city of Jerusalem was breached at the [time of] the destruction of the second Temple. And Apostimos burned the Torah and set up an image in the [Temple] chamber. And so [too] on the ninth of Av, five things also occurred. 1) It was decreed in the desert that Israel would not enter the land. 2-3) And the Temple was destroyed, the first and the second. As at the end of II Kings 25 8-9, it is written, "And on the fifth month on the ninth of the month, in the twelfth year of the reign of Nevuchadnetsar...came Nevuzaradan... and the burned the House of the Lord." And at the end of Jeremiah 52:12, it is written about this very story, "on the tenth of the month." And they said in Taanit, "It was taught, 'It is impossible to say on "on the seventh," as behold it has already been stated "on the tenth;" and it is impossible to say "on the tenth," as behold it has already been stated "on the seventh." So how is this? On the seventh, they entered the chamber, etc. On the ninth close to darkness, they set it on fire and it continued to burn the entire day of the tenth'" (Taanit 29a). 4) And Beitar was conquered on it, and there were thousands and tens of thousands of Jews [there]. And there was a king there and many imagined that he was the king Messiah. But the sins caused that they were all killed and they were also not allowed to be buried, and it was a great woe like the destruction of the Temple. 5) And on this day that is fit for punishments, the evil Turnus Rufus plowed over the [Temple] chamber, in order to fulfill that which was stated, "Zion will be plowed for a field."