[Aneinu] The Nine Days Rabbi Yirmiyohu Kaganoff (Written by the rabbi)

The Mishnah teaches that "Mishenichnas Av mema’atim b’simchah," "When Av enters, we decrease our happiness," (Taanis 26b). Although the Mishnah does not clarify exactly how we demonstrate our decreased happiness, the Gemara (Yevamos 43a) includes four activities that are banned: one should decrease one’s business activities, refrain from construction and planting intended for joyous reasons (Yerushalmi Taanis, cited by Tosafos to Yevamos 43a s.v. Milisa), not conduct weddings and not make a festive meal to celebrate an engagement. (This is the interpretation of the Gemara as explained by the Tur Orach Chayim 551 and by the Ramban in Toras Ha’adam, cf. Rashi ad loc.)