2 Sam 21:2

21:2 the people of Israel had sworn. Israel’s treaty with the Gibeonites is recorded in Josh. 9. Although Israel had been remiss in entering into such a treaty without inquiring of the Lord (Josh. 9:14), they still felt obliged to honor their word (Josh. 9:19).

in his zeal for the people of Israel and Judah. Saul’s attempt to annihilate the Gibeonites was motivated by nationalistic, not religious, zeal. He may have wanted to rid his home tribe, Benjamin, of unwanted Amorite survivors. For Saul’s ancestral association with Gibeon, see 1 Chr. 9:35–39.