1 Samuel 30:2-5

They slew not any. No resistance was made, as the men of war were all away. It was probably for thus leaving their wives and families absolutely defenceless that David's people were so angry with him. As we are told in 1 Samuel 27:3 that the refugees with David had brought each his household with him into the Philistine territory, the number of women must have been large. The Amalekites spared their lives, not because they were more merciful than David, but because women and children were valuable as slaves. All the best would be picked out, and sent probably to Egypt for sale.