Commentary for I Chronicles 20:1

וַיְהִ֡י לְעֵת֩ תְּשׁוּבַ֨ת הַשָּׁנָ֜ה לְעֵ֣ת ׀ צֵ֣את הַמְּלָכִ֗ים וַיִּנְהַ֣ג יוֹאָב֩ אֶת־חֵ֨יל הַצָּבָ֜א וַיַּשְׁחֵ֣ת ׀ אֶת־אֶ֣רֶץ בְּנֵֽי־עַמּ֗וֹן וַיָּבֹא֙ וַיָּ֣צַר אֶת־רַבָּ֔ה וְדָוִ֖יד יֹשֵׁ֣ב בִּירֽוּשָׁלִָ֑ם וַיַּ֥ךְ יוֹאָ֛ב אֶת־רַבָּ֖ה וַיֶּֽהֶרְסֶֽהָ׃

And it came to pass, at the time of the return of the year, at the time when kings go out to battle, that Joab led forth the power of the army, and wasted the country of the children of Ammon, and came and besieged Rabbah. But David tarried at Jerusalem. And Joab smote Rabbah, and overthrew it.

Rashi on I Chronicles