The Israelites spent 400 years in Egypt. They were invited to settle in Egypt to escape the famine in their own land. At first they were honored guests but that status changed.
Now there arose a new king over Egypt, who did not know Joseph. And he said to his people, “Behold, the people of Israel are too many and too mighty for us. Come, let us deal shrewdly with them, lest they multiply, and, if war breaks out, they join our enemies and fight against us and escape from the land.”
Therefore they set taskmasters over them to afflict them with heavy burdens. They built for Pharaoh store cities, Pithom and Raamses. (Exodus 1:8-11)
The people prayed to God for freedom from their bondage and God chose Moses to answer their prayers.
Then the Lord said, “I have surely seen the affliction of my people who are in Egypt and have heard their cry because of their taskmasters. I know their sufferings, and I have come down to deliver them out of the hand of the Egyptians and to bring them up out of that land to a good and broad land, a land flowing with milk and honey, to the place of the Canaanites, the Hittites, the Amorites, the Perizzites, the Hivites, and the Jebusites. And now, behold, the cry of the people of Israel has come to me, and I have also seen the oppression with which the Egyptians oppress them. Come, I will send you to Pharaoh that you may bring my people, the children of Israel, out of Egypt.” (Exodus 3:7-10)