12 Then Abner sent messengers to David at his place, saying, “Whose is the land? Make your covenant with me, and behold, my hand shall be with you to bring all Israel over to you.” 13 And he said, “Good! I will make a covenant with you, only I require one thing of you, [g]namely, that you shall not see my face unless you first bring Michal, Saul’s daughter, when you come to see [h]me.” 14 So David sent messengers to Ish-bosheth, Saul’s son, saying, “Give me my wife Michal, to whom I was betrothed for a hundred foreskins of the Philistines.” 15 Ish-bosheth sent men and [i]had her taken from her husband, from [j]Paltiel the son of Laish. 16 And her husband went with her, weeping as he went, [k]following her as far as Bahurim. Then Abner said to him, “Go, return.” So he returned.
17 Now Abner had a [l]consultation with the elders of Israel, saying, “In times past you were seeking for David to be king over you. 18 Now then, do it! For the Lord has spoken regarding David, saying, ‘By the hand of My servant David [m]I will save My people Israel from the hand of the Philistines, and from the hands of all their enemies.’” 19 Abner also spoke [n]to Benjamin; and in addition Abner went to speak [o]to David in Hebron everything that seemed good to Israel and to the entire house of Benjamin.
20 Then Abner and twenty men with him came to David at Hebron. And David held a feast for Abner and the men who were with him. 21 Abner said to David, “Let me set out and go and gather all Israel to my lord the king, so that they may make a covenant with you, and that you may be king over all that your soul desires.” So David let Abner go, and he went in peace.
22 And behold, the servants of David and Joab came from a raid and brought a large amount of plunder with them; but Abner was not with David in Hebron, since he had let him go, and he had gone in peace. 23 When Joab and all the army that was with him arrived, they informed Joab, saying, “Abner the son of Ner came to the king, and he has let him go on his way, and he has gone in peace.” 24 Then Joab came to the king and said, “What have you done? Behold, Abner came to you; why then have you let him go, so that he is already gone? 25 You know Abner the son of Ner, that he came to gain your confidence, and to learn of your [p]going out and coming in and to find out everything that you are doing.”
For sure, trusting Abner was a risk, and possibly even one David didn’t need to take. But he saw an opportunity to unite the tribes of Israel once more, and he took the chance.
However, Joab was not so trusting. Even more, he probably wanted revenge on Abner for killing his brother. He was very upset when he found out that David had let Abner go in peace.
The contrast is that David trusted God. Could Abner be trusted? Only God knew, and so David was willing to take that chance. While Joab might have been leader of David’s men, it seems his trust was more in the strength of his men. He should have known better, having seen firsthand how they had triumphed with such a small band of men over much larger foes.
Again, it’s a lesson to trust God, and look for the good in people. Not to put our trust in men, but as we seek God, to believe that He will work things out for the best. All our efforts to find the best outcome are in vain if it isn’t in God’s plan. So trust Him and follow the path He gives you.