Albert Barnes Commentary 2 Samuel 21:18

"And it came to pass after this, that there was again war with the Philistines at Gob: then Sibbecai the Hushathite slew Saph, who was of the sons of the giant." — 2 Samuel 21:18 (ASV)

A battle in Gob. In the parallel passage (marginal reference), “Gezer” is named as the field of this battle. However, Gath is named in 2 Samuel 21:20 and 2 Samuel 21:22 in a way that makes it probable that Gath was the scene of all the battles. The Septuagint in this verse has “Gath.”