Have you ever had a loose cannon? This is someone who fires a fatal shot when you least expect it. Joab was David’s loose cannon. He often took matters into his own hands without consulting David. Joab had his own agenda. He was loyal to David except when his personal passion was at stake.

David had patiently waited for seven years to rule over Israel as God had promised. When Abner defected from the house of Saul and swore to use his influence to bring the remaining eleven tribes to David, it was David’s golden opportunity. Abner, along with twenty men, came to David in Hebron, and David prepared a feast for them.

“Then Abner said to David, ‘Let me go at once and assemble all Israel for my lord the king, so that they may make a compact with you, and that you may rule over all that your heart desires.’ So David sent Abner away, and he went in peace.” (2 Samuel 3:21, NIV84)

But Joab was not present when Abner came. When he heard about it, he went to David.

“‘What have you done? Look, Abner came to you. Why did you let him go? Now he is gone! You know Abner son of Ner; he came to deceive you and observe your movements and find out everything you are doing.’” (2 Samuel 3:24–25, NIV84)

I have discovered that people often accuse others of doing things that they would do if they were in their place. Joab misjudged Abner’s motives. But he did this because of the resentment he held against Abner for killing his brother Asahel in battle. Joab wanted to settle the score. Therefore, he sent messengers to bring back Abner without telling David about it. When Abner arrived, Joab pulled him aside, as if to speak to him privately, and then he stabbed him to death! That single act of treachery and violence could have turned all of Israel away from David. But Joab only cared about avenging his brother’s blood. When David heard about this, he cursed Joab, but that could not undo the damage nor bring back Abner from the dead.

We must all beware of loose cannons.

“Hot-tempered people must pay the penalty. If you rescue them once, you will have to do it again.” (Proverbs 19:19, NLT)

“Don’t befriend angry people or associate with hot-tempered people, or you will learn to be like them and endanger your soul.” (Proverbs 22:24–25, NLT)

We cannot control when loose cannons go off (David never did tame Joab). But we can keep from being like them.