harp \harp\, v. i. imp.  p. p. harped haumrpt p. pr. 
   vb. n. harping. as. hearpian. see harp, n.
   1. to play on the harp.
      1913 webster

            i heard the voice of harpers, harping with their
            harps.                                --rev. xiv. 2.
      1913 webster

   2. to dwell on or recur to a subject tediously or
      monotonously in speaking or in writing; to refer to
      something repeatedly or continually; -- usually with on or
      upon. "harpings upon old themes." --w. irving.
      1913 webster

            harping on what i am,
            not what he knew i was.               --shak.
      1913 webster

   to harp on one string, to dwell upon one subject with
      disagreeable or wearisome persistence. colloq.
      1913 webster
see also:
harped harping harp to harp on one string