This year, Tisha B’Av is observed on Sunday, the tenth of Av, which coincides with the Daf HaYomi of Zvachim Daf Kuf. That daf deals with the halachos of Aninus – mourning. Rav Chaim was asked whether one would be permitted to learn the Daf on Tisha B’Av since it deals with the laws of mourning.
Rav Chaim answered that one may learn the Daf on that day.
The Shulchan Aruch 554:1 rules that it is generally forbidden to study Torah on Tisha B’Av. This is because Dovid HaMelech wrote in Tehillim (19:9), Pikudei hashem yesharim – the commandments of Hashem are upright, Mesamchei Laiv – they gladden the heart. This is therefore forbidden to do on Tisha B’Av.
The Maharsha in Taanis 30a cites another reason why it is forbidden to study Torah on Tisha B’Av. The other reason is that it can take one’s mind off of the Churban of the Beis HaMikdash (both of them that were destroyed on this day).
There are exceptions to the prohibition of what may be studied. These include the Tanach Sfarim of Iyov, Eicha and the sections of Yirmiyahu that deal with destruction. Sections of the Gemorah that deal with mourning and with the destruction may also be studied. Also, Rav Yisroel Salanter ruled that Mussar Seforim may be studied as well.
The Mishna Brurah 554:4 and the TaZ on that Siman indicate that one may not learn these topics in great depth. Presumably, Rav Chaim Kanievsky is assuming that when this Daf will be studied, it will not be done in great depth.
Another chidush here is that the joy that one is studying the Daf does not counter the sadness and hence the permissibility of studying the laws of mourning.
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