Exodus 1:10
Come on, let us deal wisely with them; lest they multiply, and it come to pass, that, when there falleth out any war, they join also unto our enemies, and fight against us, and so get them up out of the land. Come on, let us deal wisely with them; lest they multiply, and it come to pass, that, when there falleth out any war, they join also unto our enemies, and fight against us, and so get them up out of the land.
Joseph and all his brethren and all that generation had died, while the children of Israel were fruitful and increased abundantly and multiplied and grew exceeding mighty until the land was filled with them, and then a new king over Egypt who did not know Joseph spoke to his people. He declared to them that the children of Israel had become more and mightier than the Egyptians and had filled the land. He feared they would keep multiplying, and that when war broke out they would join Egypt's enemies, fight against Egypt, and leave or escape from the land.
He was unwilling to lose them by banishment, for their distinct customs and religion set them apart, and because they were useful workers of great service as able and understanding workmen whose labor he was not willing to lose. His call to deal wisely with them therefore meant a policy of control through enslavement. That meant reducing free Israelites to the rank of those Egyptians who had sold their flocks, herds, lands and themselves to the kingdom, and setting taskmasters over them to afflict them with burdens.