§ 02 · King James Bible
2 Samuel 21:7
But the king spared Mephibosheth, the son of Jonathan the son of Saul, because of the LORD’s oath that was between them, between David and Jonathan the son of Saul.
Simple English
But King David saved Mephibosheth, who was Jonathan's son and Saul's grandson, because they had made a promise to each other under God's guidance. This promise was between David and Jonathan, Saul's son.
* Work in progress - there may be occasional inaccuracies