Tishe Beav:[1]

The Baalei Habris may wear Shabbos clothing when a Bris takes place on Tishe Beav. The Shabbos clothing may be worn until after the Bris. However, they may not wear leather shoes.[2]

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[1] Rama 559:8

[2] Bigdei Yesha , brought in Biur Halacha 559 “Umutar”