Q. I heard that Tevet has an extra fast on the 9th of the month. Is this true?
A. 10 Tevet is well known as one of the four fasts that mark the destruction of the Temple. The Shulchan Aruch (Orach Chayyim 580:2) refers to an extra fast on 9 Tevet which some compilations of Jewish customs regard as a disapproving reflection of Jesus’ birth being on 9 Tevet, but the dating is questionable and the fast remains a mystery.