The Aja'ib was a book from Hyspero which told a series of stories which had some similarities to the lives of the Doctor and Iris Wildthyme.
Sam Jones stole the book for the Eighth Doctor while on Hyspero. (PROSE: The Scarlet Empress)
Terrance stole the Aja'ib from Hyspero and kept it in the Great Big Book Exchange. (PROSE: Enter Wildthyme)