New Defender's Study Bible Notes
21:19 slew the brother of Goliath. Since the words “the brother of” are not in the original (and, therefore, are italicized in most printings of the King James Version), critics have alleged a contradiction here with the story of David and Goliath (I Samuel 17:4,7,50). It is more reasonable, however, to assume an ancient copyist omission here, especially in view of the more complete description given in the parallel passage, as follows: “And there was war again with the Philistines; and Elhanan the son of Jair slew Lahmi the brother of Goliath the Gittite, whose spear staff was like a weaver’s beam” (I Chronicles 20:5). Another (less likely) resolution would be the possibility that this Goliath was the son of the Goliath slain by David, and that both Goliath (Jr.) and his brother Lahmi were slain by Elhanan. In either case, there is no contradiction.