Albert Barnes Commentary 1 Chronicles 20:4-5

"And it came to pass after this, that there arose war at Gezer with the Philistines: then Sibbecai the Hushathite slew Sippai, of the sons of the giant; and they were subdued. And there was again war with the Philistines; and Elhanan the son of Jair slew Lahmi the brother of Goliath the Gittite, the staff of whose spear was like a weaver`s beam." — 1 Chronicles 20:4-5 (ASV)

See the marginal reference and notes.