Charles Ellicott Commentary 1 Samuel 30:2

"and had taken captive the women [and all] that were therein, both small and great: they slew not any, but carried them off, and went their way." — 1 Samuel 30:2 (ASV)

They slew not any. There was no one in the hapless city to resist the attack of the fierce sons of the desert. David—never dreaming of the sudden invasion—had marched with Achish, accompanied by his whole force. The Amalekites slew none of their captives; they were, we read, women and children. These possessed a marketable value, and were carried off to be sold into slavery, probably in Egypt, with which country the Amalekites, as neighbours, had constant dealings. We read a few verses later specifically of an Egyptian slave in the army.