An Etymological Dictionary of the German Language/Annotated/Rast
Rast, feminine, ‘rest, repose,’ from Middle High German rast, raste, feminine, Old High German rasta, feminine, ‘repose, rest, permanence,’ also in Old High German and Middle High German ‘stage of a journey,’ which is the only sense borne by Gothic rasta and Old Icelandic rǫst. Compare Anglo-Saxon rœst, English rest, Old Saxon rasta, ręsta, ‘couch, deathbed,’ Dutch rust (see Rüste), ‘rest, repose.’ The common Teutonic word is based on a root ras, ‘to remain, dwell,’ which may also be inferred from Gothic razn and Old Icelandic rann, ‘house.’ Rast, in the sense of ‘stage,’ comes from the period when the Western Aryans were migrating to Europe; only a wandering tribe could adopt the intervals of reposing and encamping as a measure of distances. Moreover, the older language preserves a few other words as relics of the migratory period; compare Middle High German tageweide, feminine, ‘day's journey, the distance traversed in a day’ (properly said of nomadic marches, ‘the length of pasture grazed by cattle in one day’); see Hanf. Whether the assumed root ras, ‘to remain, dwell,’ is connected with the root rô in Ruhe is doubtful.