An Etymological Dictionary of the German Language/be-

by Friedrich Kluge

be-, prefix from MidHG. be, properly a verbal prefix from OHG. and Goth. bi, which has no definite meaning; identical with the prep. bei, from OHG. and MidHG. bî (Goth. bi), AS. bî, E. by. For be there appears a shorter syncopated form in bange, Erbarmen? barsch? bleiben, Block. See specially bei.