Exodus 12 verses 21 -28
Then Moses called all the elders of Israel together and said to them,
“Go, pick out a lamb or young goat for each of your families, and slaughter the Passover animal. Drain the blood into a basin. Then take a bundle of hyssop branches and dip it into the blood. Brush the hyssop across the top and sides of the doorframes of your houses. And no one may go out through the door until morning. For the LORD will pass through the land to strike down the Egyptians. But when he sees the blood on the top and sides of the doorframe, the LORD will pass over your home. He will not permit his death angel to enter your house and strike you. Remember, these instructions are a permanent law that you and your descendants must observe forever.
When you enter the land the LORD has promised to give you, you will continue to observe this ceremony. Then your children will ask, ‘What does this ceremony mean?’ And you will reply, ‘It is the Passover sacrifice to the LORD, for he passed over the houses of the Israelites in Egypt. And though he struck the Egyptians, he spared our families.’”
When Moses had finished speaking, all the people bowed down to the ground and worshiped. So the people of Israel did just as the LORD had commanded through Moses and Aaron.
Exodus 12 verses 40-42
The people of Israel had lived in Egypt for 430 years. In fact, it was on the last day of the 430th year that all the Lord’s forces left the land. On this night the Lord kept his promise to bring his people out of the land of Egypt. So this night belongs to him, and it must be commemorated every year by all the Israelites, from generation to generation.
From the New Living Translation