Rivers of Rassilon

The Twelfth Doctor mentally swore "by the Rivers of Rassilon" when exasperated by his earlier self's antics regarding their disagreement on proper TARDIS control console interiors. (PROSE: Twice Upon a Time)

Behind the scenes

 * The reference to the Rivers of Rassilon in Twice Upon a Time is too fleeting to clarify whether the Rivers somehow constitute Artefacts of Rassilon, or if the similarity in naming scheme to such items as the Harp of Rassilon is merely coincidental and the Rivers are mundane bodies of water merely named after the Time Lord dictator.