The Collaborative International Dictionary of English v.0.48:

Daysman \Days"man\ (d[=a]z"m[a^]n), n. [From day in the sense of
   day fixed for trial.]
   An umpire or arbiter; a mediator.
   [1913 Webster]

         Neither is there any daysman betwixt us. --Job ix. 33.
   [1913 Webster]