"Rabbath of the children of Ammon," the chief city of the Ammonites, among the eastern hills, some 20 miles east of the Jordan, on the southern of the two streams which united with the Jabbok. Here the bedstead of Og was preserved (Deuteronomy 3:11), perhaps as a trophy of some victory gained by the Ammonites over the king of Bashan. After David had subdued all their allies in a great war, he sent Joab with a strong force to take their city. For two years it held out against its assailants. It was while his army was engaged in this protracted siege that David was guilty of that deed of shame which left a blot on his character and cast a gloom over the rest of his life. At length, having taken the "royal city" (or the "city of waters," 2 Samuel 12:27, i.e., the lower city on the river, as distinguished from the citadel), Joab sent for David to direct the final assault (11:1; 12:26-31). The city was given up to plunder, and the people were ruthlessly put to death, and "thus did he with all the cities of the children of Ammon." The destruction of Rabbath was the last of David's conquests. His kingdom now reached its farthest limits (2 Samuel 8:1-15; 1 Chronicles 18:1-15). The capture of this city is referred to by (Amos 1:14), (Jeremiah 49:2,3), and (Ezekiel 21:20; 25:5).
A city in the hill country of Judah (Joshua 15:60), possibly the ruin Rubba, six miles north-east of Beit-Jibrin.
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Rabbah'". "Easton's Bible Dictionary". <http://classic.studylight.org/dic/ebd/view.cgi?number=T3043>. 1897.