2 Samuel 21:1, commentary and pictures

The Gibeonites were still flourishing in the time of David as a free people with political rights, able to make their own treaty with the king of Israel, and though they served as public servants that service did not make them chattel slaves, for they remained personally free with their own homes and land and families. They had first obtained the protection of Israel by craft and deception, yet the league and oath made with Joshua in the name of God remained sacred and binding upon later generations. In the days of David there was famine three years in succession, year after year, because Saul and his bloody house had shed the blood of the Gibeonites and done violence against them. The cause became known because David inquired of the Lord and the Lord answered him, showing that God had not forgotten the injustice.

Saul had killed some of the Gibeonites and apparently planned to massacre the rest, and this bloodshed by him and his house brought suffering upon the land. God's anger over this treacherous violation of the oath was appeased when seven of Saul's descendants were put to death for his crime. An individual's offense could be reckoned against his whole family, so that Saul's violence brought consequences upon his house. God holds the whole people responsible for the transgressions of a few when the rest allow the sin to continue.

A leader's mistake can bind the people and bring consequences upon the nation long afterward, even though the leader is not removed from his position. God opposes oppression even when its victims are not of the household of faith. The episode belongs with David's continued kindness toward the house of Saul. The famine among his people, alongside a plague, was one of the afflictions in David's life that served as discipline to form his humility and noble character and deep piety.