1,393. Other Ways in Which We Commemorate the Destruction

Hilchos Taaniyos 5:13

The Sages similarly decreed that one who sets a table for guests should serve a little bit less and also leave an empty place, omitting one of the settings that would otherwise be placed there. When a woman has jewelry made, she should leave out one piece that would otherwise be in the set so that her jewelry is incomplete. Similarly, when a man gets married, he should place ashes on the place on the head where tefillin goes. These practices were instituted to remind us of Jerusalem, as per Psalms 137:5-6, “If I forget you, Jerusalem, may my right hand forget its skill. May my tongue cleave to my palate if I do not remember you, if I do not place Jerusalem above my greatest joy.”

Hilchos Taaniyos 5:14

They likewise decreed that one should not play songs on any kind of musical instrument. It is prohibited to celebrate with musical instruments or to listen to them being played in memory of the destruction. Even singing is prohibited while drinking wine, as per Isaiah 24:9, “Do not drink wine with song.” The accepted practice of Jewry, however, is to sing things like words of praise and songs of thanks to God over wine.