The Weekly Mitzva - Vayeshev, Fasting in the Wake of a Bad Dream, by Rav Yair Kahn
The shiur deals with the unique halacha of a "taanit chalom" and discusses how this fast circumvents the standard requirement of accepting a personal fast on one's self the previous day and why it is permitted to fast a "taanit chalom" on Shabbat.
