CHAPTER 20 Oct. 5 
At the time of the return of the year, at the time when kings go out, Joab led forth the army, and wasted the country of the children of Ammon, and came and besieged Rabbah. But David stayed at Jerusalem. Joab struck Rabbah and overthrew it. 2David took the crown of their king from off his head, and found it to weigh a talent of gold, and there were precious stones in it; and it was set on David’s head; and he brought forth the spoil of the city, a great amount. 3He brought forth the people who were therein, and cut them with saws, and with iron picks, and with axes. David did so to all the cities of the children of Ammon. David and all the people returned to Jerusalem. 
The Sons of the Giant Are Killed
4After this, there arose war at Gezer with the Philistines. Then Sibbecai the Hushathite killed Sippai, of the sons of the giant; and they were subdued. 5There was again war with the Philistines; and Elhanan the son of Jair killed Lahmi the brother of Goliath the Gittite, the staff of whose spear was like a weaver’s beam. 6There was again war at Gath, where there was a man of great stature, whose fingers and toes were twenty-four, six on each hand, and six on each foot; and he also was born to the giant. 7When he defied Israel, Jonathan the son of Shimea David’s brother killed him. 8These were born to the giant in Gath; and they fell by the hand of David, and by the hand of his servants.

Commentary

20:1 But David stayed at Jerusalem- 2 Sam. 11 fills in the significant detail that during this period, David had an affair with Bathsheba and arranged for her husband Uriah to be killed. Simple lesson: to properly understand the Bible we must read it all and compare it against itself in order to get the fill picture.
20:3 This seems an unnecessarily cruel way of punishing enemies. This is the period in between David’s sin with Bathsheba and his repentance. His own bad conscience with God led him to such excessive punishment of God’s enemies. Psychologically, it’s understandable; he realized he had sinned and deserved to be punished. But instead of confessing his sin and accepting the consequences as rightful and just, he psychologically transferred the sin onto others, and punished them instead of seeing himself punished. Judgmentalism and aggressive attitudes toward others often arise from a bad conscience within a person; the answer is to confess our sins to God, repent before Him and accept any consequences. We are thereby made free from the need to transfer sin and guilt onto others and judge them for our own sin.
20:5-8 These battles with giant Philistines have many similarities with David’s victory over Goliath in 1 Sam. 17. His victory there inspired his men, just as Christ’s victory on the cross [‘Golgotha’ = ‘skull of Goliath’] should inspire us and be replicated by us in our spiritual struggles.