Chapter 122:15 Between the 17th of Tammuz and Tisha B'av
15. When a "bris" ("circumcision") is held during these nine days [between
Rosh Chodesh Av and Tish'ah B'av], the "mohel" (one who performs the
circumcision), the "sandok" (one who holds the baby on his lap during the
circumcision), and the child's parents are permitted to wear their Shabbos
clothing (1). The man who brings the baby [into the room where the bris
will be performed] (the "qwatter"), may not wear his Shabbos clothes. In
contrast, the woman who brings the baby in (the "qwaterrin") may do so,
because this is the totality of her mitzvah.
[The three men mentioned above] may also cut their hair (and shave) [if the
bris is held] before Shabbos Chazon (that is, before the week in which
Tish'ah B'av occurs, begins). Afterwards, this is forbidden.
(1) As we saw in HY 122:9 (b), during the nine days it is forbidden to wear
or spread freshly laundered clothing or linen (except on Shabbos), even if
they were washed before the nine days.