An Etymological Dictionary of the German Language/Annotated/euch
Appearance
euch, pronoun, ‘you, to you,’ from Middle High German iuch, iuwich, Old High German iuwih, accusative, the dative of which, however, is in in Middle High German and Old High German; compare Anglo-Saxon eów (and eówic), accusative, eow, dative (English you), Gothic izwis, accusative, dative. Is Latin vos, vester, akin? All other references are dubious. —