Dirij Tereur

The fifth of Frost Fall marks Dirij Tereur for the people of the Alik'r Desert. It is a sacred day honoring Frandar Hunding, the traditional spiritual leader of the Redguards who led them to Hammerfell in the first era. Stories are read from Hunding's Book of Circles, and the temples in the region are filled to capacity.

(Source)

http://www.imperial-library.info/content/calendar-tamriel