2 Samuel 21:1-3

THERE WAS a three-year famine in the days of David, year after year; and David inquired of the Lord. The Lord replied, It is on account of Saul and his bloody house, for he put to death the Gibeonites. So the king called the Gibeonites–now the Gibeonites were not Israelites but of the remnant of the Amorites. The Israelites had sworn to spare them, but Saul in his zeal for the people of Israel and Judah had sought to slay the Gibeonites– So David said to the Gibeonites, What shall I do for you? How can I make atonement that you may bless the Lord's inheritance?