Exodus 1:11-14

So they set taskmasters over them to oppress them with hard labor. And the sons of Israel built Pithom and Raamses as storage cities for Pharaoh. But the more the Egyptians oppressed them, the more they multiplied and expanded, so that the Egyptians dreaded and were exasperated by the Israelites. And the Egyptians made the Israelites serve rigorously [forcing them into severe slavery]. They made their lives bitter with hard labor in mortar, brick, and all kinds of field work. All their labor was harsh and severe.