The prophet Zechariah 7:3 brings a question he was asked by Jews during the Second Temple as to whether or not they should continue fasting on Tisha B'av, presumably because the Temple had been rebuilt. The prophet goes on to give a long prophesy about all the Jew's desecrations of God's law over the years, and about the salvation that God and is going to bring them. All this is interpolated repeatedly with the phrase "so says God", which is generally taken by the commentaries to mean that this is a new prophesy/statement. Finaly, in Zechariah 8:19 the prophet states that in the future all the fast days will be days of rejoicing. My question is, is this verse a reponse to the halachik inquiry of the earlier verse, meaning that he was instructing them to fast?
An article by the Campus Rabbi of Bar Ilan University states:
In his commentary to the Mishnah (Rosh Hashanah 1,3), Maimonides states that the Jews in the Second Temple period fasted on Tishah B'av.
This was not a copier’s error. Indeed,
In the fifth chapter of Hilchot Ta'aniot, halachah 5, after Maimonides listed the four fast days commemorating the destruction of the Temple, he adds: "It was the custom in all of Israel to fast on these days, and on the 13th of Adar in remembrance of the fasts which were observed in the time of Haman", etc.
The Campus Rabbi points out that:
The S'fat Emet (in his commentary to Rosh Hashanah, op. cit.) explains that even according to Maimonides fasting on Tishah B'av was not observed during the entire period of the Second Temple and its observance was dependent on the changing political situation from time to time: When the Jews of the Second Temple were under the yoke of foreign rule, that was considered a time when there was "no peace" and then fasting was observed, but when Jews ruled themselves (as during the Hasmonean period),that was a period of peace and the fast of Tishah B'av was canceled .
Some doubt does exist as to whether the explanation of the S'fat Emet truly reflects the ideas of Maimonides. No mention is made by Maimonides of any differentiation between various portions of the Second Temple period. The implication is simply that during that whole time, even during periods of political independence, fasting was observed on Tishah B'av.
I suggest therefore that if Zechariah had responded to the halachik inquiry of the earlier verse and instructed them to fast, this would fit well with the view of the Rambam.
It might be possible to take a more nuanced view based on the S'fat Emet that he instructed them to fast only when they were under the yoke of foreign rule