Five Tenets

The Five Tenets are a set of rules the Dark Brotherhood followed up to and during the Oblivion Crisis, but was later abandoned when the Brotherhood began to wane. During Oblivion, breaking these tenets can result in suspension from the guild. Repeat rule-breaking can then lead to further consqeuences.

During Skyrim, Astrid states that the Brotherhood stopped following the tenets, as she believed they are the real reason the brotherhood fell into decline.

There is a book in Oblivion that can be found in Fort Farragut, the sanctuary, or in the inventories of several of the brotherhood members that states the tenets. They are:

Tenet 1: Never dishonor the Night Mother. To do so is to invoke the Wrath of Sithis.

Tenet 2: Never betray the Dark Brotherhood or its secrets. To do so is to invoke the Wrath of Sithis.

Tenet 3: Never disobey or refuse to carry out an order from a Dark Brotherhood superior. To do so is to invoke the Wrath of Sithis.

Tenet 4: Never steal the possessions of a Dark Brother or Dark Sister. To do so is to invoke the Wrath of Sithis.

Tenet 5: Never kill a Dark Brother or Dark Sister. To do so is to invoke the Wrath of Sithis.

In Skyrim, old copies of the tenets can be seen framed on the walls of both sanctuaries.