Malbim: When he saw that David did not want to punish them, he thought that it is proper to punish them. Not only will they not receive the general spoils - they will not receive even their own property that was recovered, just their wives and children (for Nochrim cannot acquire Jews).

Malbim: They were brazen to speak against David, they cast of the yoke ¹ , and they were stingy about their brothers.