In 2 Samuel 21 we see the importance of covenants to God. Famine comes upon the land of Israel because of Saul’s decision to annihilate the Gibeonites, and atonement for this sin is required. The back story to this is found in Joshua 9 and 10 when Israel first entered the promised land. The people of Gibeon saw Israel’s success in defeating Jericho and Ai, and decided to make peace through deception, pretending they had come from far away. God’s people did not inquire of the Lord and made a covenant not to harm them; centuries later, this covenant still applied.
Saul, presumably, did not feel that a covenant made hundreds of years before had any relevance to him, but God does not forget promises made, and blessings and curses are the result of how we respond to these. He is a covenant-keeping God and expects the same of His people. David, seeking God as to the reason for the famine on the land, is told that this is because of Saul’s actions against the Gibeonites and he asks them what they want. He hands over seven of Saul’s descendants to be killed as atonement, sparing Mephibosheth because of his own covenant to Jonathan.
The story may seem harsh to us, but it reminds us very clearly of the importance of making promises and keeping them, and the binding nature of covenant. We do well to understand this before making vows (see Eccl 5:4, Matt 5:37, Mal 2:13-16). We cannot live as though the past has no impact on the present. ‘Old sins have long shadows’, as the proverb goes, and we do well to seek God for guidance in these matters.