An Etymological Dictionary of the German Language/flehen
flehen, vb., ‘to implore, supplicate,’ from MidHG. vlêhen, OHG. flêhan, flêhôn, ‘to implore,’ OHG. also ‘to fondle, flatter’; initial fl for earlier þl, as in fliehen (Goth. þliuhan); comp. Goth. gaþláihan (ai a genuine diphthong), ‘to fondle, embrace, console, exhort in a friendly way,’ akin to Goth. gaþláihts, f., ‘comfort, warning.’ Also allied to OIc. flár, ‘false, cunning,’ AS. flâh. ‘wily, cunning,’ both pointing to Goth. *þlaiha-. The primary meaning of the root flaih was perhaps ‘importunate, insinuating speech.’