Introduction to the Prohibitions of the Mourner (2) – Moed Katan 14b to 16a, summary
The gemara in Moed Katan (from 14b until 16a) addresses fourteen different behaviors that are either required or forbidden by a mourner: observance during a Holiday, haircuts, head-covering, wearing Tefillin, greeting, learning Torah, laundry, tearing garments, over-turning the bed, work, washing, wearing leather shoes, sexual intercourse and sending sacrifices to the Beit ha-Mikdash. The sugya is confident about the rules relating to the mourner and quotes a verse (or one berayta) to prove the rule. After clarifying the rule for a mourner, the sugya then seeks to understand how that same rule does or does not apply to one who has been excommunicated and a person with tzara’at1.
Here is an example of that structure:
תלמוד בבלי מסכת מועד קטן דף יד עמוד ב
אבל אסור בתספורת מדקאמר להו רחמנא לבני אהרן (ויקרא י:ו) רָאשֵׁיכֶם אַל תִּפְרָעוּ
מכלל דכולי עלמא אסור (דף טו עמוד א).
מנודין ומצורעין מה הן בתספורת?
תא שמע מנודין ומצורעין אסורין לספר ולכבס…
Bavli, Moed Katan, 14b
A mourner is prohibited from cutting their hair, as the merciful one taught in the Torah to the children of Aharon, “Do not bare your heads” (Vayikra 10:6) –
from this we learn that everyone else is prohibited from cutting their hair.
Those who have been excommunicated and those with tzara’at – what is their rule regarding haircuts?
Come and hear: Those who have been excommunicated and those with tzara’at are prohibited from cutting their hair… …