After the year was expired. — Heb., at the time of the return of the year: i.e., in spring. (See 1 Kings 20:22; 1 Kings 20:26.)
At the time that kings go out. — See 1 Kings 20:16. Military operations were commonly suspended during winter. The Assyrian kings have chronicled their habit of making yearly expeditions of conquest and plunder. It was exceptional for the king to “remain in the country.”
Joab led forth the power of the army. — Samuel gives details: “David sent Joab and his servants (? the contingents of tributaries, 1 Chronicles 19:19), and all Israel” (i.e., the entire national array).
Wasted the country. — An explanation of Samuel: “wasted the sons of Ammon.”
Rabbah, or Rabbath Ammon, the capital. (See 2 Samuel 11:1; Amos 1:14; Jeremiah 49:2-3.)
But David tarried (Heb., was tarrying) at Jerusalem. — While Joab’s campaign was in progress-In 2 Samuel 11:1 this remark prepares the way for the account which there follows of David’s temptation and fall.
And Joab smote Rabbah, and destroyed it. — A brief statement, summarizing the events related in 2 Samuel 11:27. From that passage we learn that, after an assault which doubtless reduced the defenders to the last stage of weakness, Joab sent a message to David at Jerusalem to come and appropriate the honours of the capture. Our 1 Chronicles 20:2, which abruptly introduces David himself as present at Rabbah, obviously implies a knowledge of the narrative as it is told in Samuel, and would hardly be intelligible without it. Whether the chronicler here and elsewhere borrows directly from Samuel, or from another document depending ultimately on the same original as Samuel, cannot certainly be decided.