When Ish-Bosheth got news about the death of Abner, he ‘lost courage’, that’s because he knew his time was up. Because his strength didn’t come from the Lord and the only real strength he had was in Abner, he now knows that his reign as king was coming to an end.
The sons of Rimmon, Baanah and Rekab, weren’t Israelites but possibly Amorites or Canaanites, we know this because Rimmon was from a Gibeonite city, Joshua 9:1-26. The Gibeonites were severely persecuted by Saul who murdered many of them, 2 Samuel 21:1-14. As a result of this persecution, the Gibeonites fled to Gittaim and the town of Beeroth which were considered to be a part of Saul’s tribe, Benjamin.
Mephibosheth was Johnathon’s son, the only surviving heir of Saul’s family and here it describes his fate. Verse 4 lays the foundation for what’s coming up in 2 Samuel 9, where David meets him. Notice his nurse picked him up but was in such a hurry that Mephibosheth fell and became disabled, 2 Samuel 9:13.
Notice what Rekab and Baanah did when they got inside Ish-Bosheth’s house, They stabbed him, killed him and then cut off his head. Once more treachery was involved in the death of a king who would reign in Israel. The reason Rekab and Baanah took the head of Ish-Bosheth to David, was because they wanted a reward for killing one of David’s rival kings.
David doesn’t mix his words or feelings here, when Rekab and Baanah tell him they have killed, Mephibosheth. He reminds them of what he did to the Amalekite who reported to David that he killed Saul and was looking for a reward, 2 Samuel 1:1-15.
David hates this kind of murderous act, especially when those who do them, seek some kind of political reward for doing so. David demands Mephibosheth’s blood which means he wants to hold the murderers guilty and execute them, Genesis 9:51 / Genesis 42:22 / Psalm 9:12.
We must remember that God commanded murders to be put to death, Genesis 9:6 and we must remember that God hears things we can’t hear, one of those things is unavenged blood, Genesis 4:10.
David wastes no time here in putting Rekab and Baanah to death, he didn’t really have any other choice, because if he allowed them to live, then people may think that he was part of the plan to kill Mephibosheth.
However, by killing them straight away, David sent a clear message out to all of Israel, that no one of honour should be murdered by treacherous men, 2 Samuel 1:14-16. No one can approach him to look for some kind of political reward for doing something so evil.