In 2 Samuel 16, Shimei accuses David of having murdered Saul’s relatives, and says God is punishing him for it. David makes no objection to this claim, and accepts that this message and curse are from God. But what Shimei claimed David had done is not at all what the Bible says actually happened.

David had sworn that he would not kill off Saul’s descendants. He eventually broke his promise, but that wasn’t till 2 Samuel 21, and it was with God’s approval. God very much wanted David to kill Saul’s relatives.

In the meantime, David had consistently strongly opposed the killing of any relatives of Saul. When Joab stabbed Saul’s cousin Abner to death, David declared that he had nothing to do with Joab’s crime. And then he put a curse on Joab’s family, and later had his son kill Joab for murdering Abner. Then when some other people stabbed Saul’s son Ish-Bosheth to death, David called them wicked and immediately had them killed.