Exodus 1:11-14

Therefore they set taskmasters over them to afflict them with heavy burdens. They built for Pharaoh store cities, Pithom and Raamses. But the more they were oppressed, the more they multiplied and the more they spread abroad. And the Egyptians were in dread of the people of Israel. So they ruthlessly made the people of Israel work as slaves and made their lives bitter with hard service, in mortar and brick, and in all kinds of work in the field. In all their work they ruthlessly made them work as slaves.