An Etymological Dictionary of the German Language/werben
werben, vb., ‘to sue (for), solicit,’ from MidHG. wërben (wërven), OHG. wërban, wërvan (earlier hwërfan), str. vb., ‘to turn, walk to and fro, strive hard, make an effort, be active, be doing something, accomplish something.’ For the evolution of meaning of ModHG. werben, comp. Lat. ambire. The lit. sense of the Teut. root hwërf is ‘to move to and fro,’ as is shown by Wirbel. Comp. OSax. hwërƀan, ‘to walk to and fro,’ Du. werven, ‘to woo,’ Goth. hwaírban (and hwarbôn), ‘to wander.’ A corresponding Aryan root qerp (kerp) is not found in non-Teut. Comp. Werft (2).