In the Parker Pyne short story Death on the Nile, Mohammed is a dragoman (guide and interpreter) on board the S.S. Fayoum which cruised on the Nile. Mohammed is described as "an imposing and richly dressed personage whom nothing could disturb", which is just as well, for he bore the brunt of the bad temper of Lady Ariadne Grayle during the cruise.
It was Mohammed's duty to take and guide passengers on shore excursions. He was disappointed that Parker Pyne was on board the boat, declined to go ashore to visit the Temple of Abydos.
Mohammed probably also had the role of steward because, one night, he roused Parker Pyne to tell him that Lady Ariadne Grayle had taken ill.