2 Maccabees 10:15–17

Besides that, the Idumaeans, who were in possession of important strongholds, harassed the Jews and did their utmost to keep the feud going by welcoming the refugees from Jerusalem. But Maccabaeus and his men, after solemnly imploring and beseeching God to fight on their side, rushed at the strongholds of the Idumaeans and, after a vigorous assault, captured the positions, beating off those who manned the walls, slaying any whom they came across, and slaughtering no fewer than twenty thousand.