| Barnes' Notes on the Bible This chapter, containing such other warlike exploits belonging to David's reign as the writer of Chronicles thinks it important to put on record, is to be compared with the passages of Samuel noted in the marginal references.
Clarke's Commentary on the BibleAfter the year was expired, at the time that kings go out to battle - About the spring of the year; see the note on 2 Samuel 11:1. After this verse the parallel place in Samuel relates the whole story of David and Bath-sheba, and the murder of Uriah, which the compiler of these books passes over as he designedly does almost every thing prejudicial to the character of David. All he states is, but David tarried at Jerusalem; and, while he thus tarried, and Joab conducted the war against the Ammonites, the awful transactions above referred to took place.
Gill's Exposition of the Entire BibleSee Gill on 1 Chronicles 20:1, 2 Samuel 11:1, 1 Chronicles 20:2, 2 Samuel 12:30, 2 Samuel 21:15, and 1 Chronicles 21:1.
Geneva Study BibleAnd it came to pass, that after the year was expired, at the time that kings go out to battle, Joab led forth the power of the army, and wasted the country of the children of Ammon, and came and besieged {a} Rabbah. But David tarried at Jerusalem. And Joab smote Rabbah, and destroyed it. (a) Which was the chief city of the Ammonites.
King James Translators' Notesafter...: Heb. at the return of the year
Scofield Reference NotesMargin David Here should be read 2Sam 11:2-12:25 Ps 51:1-19.
Jamieson-Fausset-Brown Bible CommentaryCHAPTER 20 1Ch 20:1-3. Rabbah Besieged by Joab, Spoiled by David, and the People Tortured. 1. at the time when kings go out to battle-in spring, the usual season in ancient times for entering on a campaign; that is, a year subsequent to the Syrian war. Joab led forth the power of the army, and wasted the country . of Ammon-The former campaign had been disastrous, owing chiefly to the hired auxiliaries of the Ammonites; and as it was necessary, as well as just, that they should be severely chastised for their wanton outrage on the Hebrew ambassadors, Joab ravaged their country and invested their capital, Rabbah. After a protracted siege, Joab took one part of it, the lower town or "city of waters," insulated by the winding course of the Jabbok. Knowing that the fort called "the royal city" would soon fall, he invited the king to come in person, and have the honor of storming it. The knowledge of this fact (mentioned in 2Sa 12:26) enables us to reconcile the two statements-"David tarried at Jerusalem" (1Ch 20:1), and "David and all the people returned to Jerusalem" (1Ch 20:3).
Matthew Henry's Concise Commentary20:1-8 David's wars. - Though the Lord will severely correct the sins of his believing people, he will not leave them in the hands of their enemies. His assistance will overcome all advantages of number and strength of those that defy his Israel. All that trust in Christ, shall be made more than conquerors through him that loveth them.
Matthew Henry's Whole Bible CommentaryChapter 20 Here is a repetition of the story of David's wars, I. With the Ammonites, and the taking of Rabbah (v. 1-3). II. With the giants of the Philistines (v. 4-8). Verses 1-3 How the army of the Ammonites and their allies was routed in the field we read in the foregoing chapters. Here we have the destruction of Rabbah, the metropolis of their kingdom (v. 1), the putting of their king's crown upon David's head (v. 2), and the great severity that was used towards the people, v. 3. Of this we had a more full account in 2 Sa. 11, 12, and cannot but remember it by this sad token, that while Joab was besieging Rabbah David fell into that great sin in the matter of Uriah. But it is observable that, though the rest of the story is repeated, that is not: a hint only is given of it, in those words which lie here in a parenthesis-But David tarried at Jerusalem. If he had been abroad with his army, he would have been out of the way of that temptation; but, indulging his ease, he fell into uncleanness. Now, as the relating of the sin David fell into is an instance of the impartiality and fidelity of the sacred writers, so the avoiding of the repetition of it here, when there was a fair occasion given to speak of it again, is designed to teach us that, though there may be a just occasion to speak of the faults and miscarriages of others, yet we should not take delight in the repetition of them. That should always be looked upon as an unpleasing subject which, though sometimes one cannot help falling upon, yet one would not choose to dwell upon, any more than we should love to rake in a dunghill. The persons, or actions, we can say no good of, we had best say nothing of. | 
