1 Chronicles 11:6
And David said, Whosoever smiteth the Jebusites first shall be chief and captain. So Joab the son of Zeruiah went first up, and was chief.
Cross-reference
In 1 Chronicles 18:15, Joab is over the army, showing his continued role as commander from the earlier promotion.
In 1 Chronicles 19:8, Joab leads Israel's army in battle, acting in the command he gained by his exploit.
In 1 Chronicles 27:34, Joab is again listed as commander of the king's army, consistent with his chief position.
Joshua 15:16 parallels this reward: Caleb offers his daughter to whoever conquers Kiriath Sepher.
Joshua 15:17 records Othniel winning Caleb's daughter — a parallel to Joab winning command by striking first.
1 Samuel 17:25 offers reward to the killer of Goliath — another reward-for-victory parallel to Joab's incentive.
2 Samuel 8:16 confirms Joab as commander of the army — the outcome of the reward promised here.
In 2 Samuel 5:8, the same capture of Jerusalem is described with David's challenge to strike the Jebusites.
In 2 Samuel 20:23, Joab is listed as commander of the army, confirming the promotion he earned by striking the Jebusite first.