Charles Ellicott Commentary 1 Samuel 30:3

"And when David and his men came to the city, behold, it was burned with fire; and their wives, and their sons, and their daughters, were taken captive." — 1 Samuel 30:3 (ASV)

And behold, it was burned with fire. —A terrible reception for David and his free lances, on their return from their ill-omened expedition with the great Philistine army, to find only the charred and smoking ruins of their homes; not one of all their dear ones, whom they had left behind—as they thought, in security—was left to tell the story of the disaster.

It was an Egyptian slave who gave them the details—one who had fallen sick and, consequently, been deserted, and whom David’s men came upon during the pursuit. He told them the story of the invasion and described the route the marauding force had taken on their return to their country.