1 Samuel 30:2

Slew not any. This was not because of mercy, but because the women and children would bring good prices as slaves and concubines. It seems to have been a custom among the warring nations of the Near East to preserve women and children, especially virgins and female children (see Num. 31:15-18; Judges 21:1-24). David had acted unwisely in leaving Ziklag without protection.

David was probably hoping that his recent trips into the desert had deterred marauders from attempting raids for a time. He was anxious to make as good an impression as possible on the Philistine host by going north with Achish. He had evidently not counted on the news of the Philistine campaign, recently completed, filtering through to the desert so quickly (see on ch. 27:9).