An Etymological Dictionary of the German Language/Reue
Reue, f., ‘repentance, from MidHG. riuwe, f., ‘sadness, pain, mourning, repentance,’ OHG. riuwa, earlier hriuwa, f.; corresponding to Du. rout, AS. hreów, ‘grief, mourning, repentance.’ Allied to an obsolete OHG. vb. hriuwan, MidHG. riuwen, ‘to feel pain, be sorry’; corresponding to AS. hreówan, ‘to vex, grieve,’ E. to rue, to which ruth is akin; OIc. hryggva, ‘to sadden.’ Goth. *hriggwan wanting. The Teut. hrū̆, ‘to be sad, sadden,’ has no correspondences in the other Aryan languages.