'SARAH, born Hingham, MA 20 July 1721 (HVR 1:290); living 1760/1 when her last child was born; married 11 June 1740 HENRY WASHBURN of Bridgewater, MA, son of Benjamin, [son of] Jonathan, [son of ] John, [son of John].'
Benjamin, son of Jonathan was most likely the Benjamin Washburn who married Martha Kingman in 1729 (see Person talk:Benjamin Washburn (6)). Henry could not have been their child. Therefore, either Benjamin son of Jonathan had an earlier marriage, or Henry was not his son and this source is incorrect. Another Benjamin Washburn (son of Samuel) married Martha's sister Bethiah in 1713/14. Given the lack of evidence for an earlier marriage for Benjamin son of Jonathan, it is not unreasonable to assume that Henry was actually the son of Benjamin son of Samuel, instead of Benjamin son of Jonathan (and that this source is incorrect). The Bridgewater VRs do not list the births of any children of Benjamin and Bethiah.