This coming Shabbat, which precedes Tisha Be’av, is referred to as Shabbat “Chazon” because of the Haftara read after the weekly Torah portion which begins with the words “Chazon Yeshayahu ben Amotz.” The three Shabbatot preceding Tisha Be’av are referred to as the “Three of Calamity” because the Haftarot of these three Shabbatot discuss the prophet’s rebuke of the Jewish nation, the destruction of the Bet Hamikdash, and the sins that caused it.
The Shabbatot following Tisha Be’av are referred to as the “Seven of Consolation” since the Haftarot read on these Shabbatot discuss words of comfort and Hashem’s boundless love for the Jewish nation even when they are in exile. When Maran Rabbeinu Ovadia Yosef zt”l would read the words of the prophets in these Haftarot, which are filled with Hashem’s love for His Jewish nation, he would become emotional and shed tears as he read the sacred words in a choked voice as he became overcome with a feeling of love, sensitivity, closeness to Hashem and His nation. Everyone present would follow suit and take advantage of the great emotional atmosphere.
One should not change anything about this Shabbat that precedes Tisha Be’av and it should be treated no differently than any of the other Shabbatot of the year, whether with regards to the foods being served, the songs being sung, and certainly with regards to not mentioning anything to do with the destruction of the Bet Hamikdash and the mourning thereof on Shabbat. Indeed, Maran Ha’Chida (Chapter 591) writes that the custom in the Land of Israel, Egypt, and many large cities in Turkey was not to change anything on Shabbat “Chazon” from the regular practice of Shabbatot throughout the year; food should be served in the regular manner of all Shabbatot in order to show the proper respect for the holy Shabbat.
Maran Ha’Chida continues that some had the custom to recite some haunting poems on this Shabbat in observance of the impending Tisha Be’av. He writes that this is an incorrect custom, especially since this is being done in a synagogue which constitutes a public display of mourning on Shabbat, which is halachically forbidden. This custom should therefore be abolished. Maran Rabbeinu Ovadia Yosef zt”l rules likewise (Chazon Ovadia-Arba Ta’aniyot, page 155).
It is permissible to sing holy songs joyously on this Shabbat, for we have already explained that even regarding weekdays preceding Tisha Be’av, there is no prohibition to sing, for only music produced by instruments may not be listened to during this period. Certainly then, singing holy songs joyously on the holiest of days is permissible and recommended.