Exodus 12: 1 -28

God delivered the Israelites from the bondage of the Egyptians. God told Moses to instruct the people to prepare meal consisting of lamb, unleavened bread and bitter herbs. The blood of the lamb should be sprinkled on the two doorposts and the lintel of the house. This was a sign for the Angel to Passover the marked houses.  the first-born male of the Egyptians as well as the first born among the animals were to be killed that night. We see an Israelite family with the lamb for the meal and the young boy holding the cup for the blood.   This event relates to Christ, our Paschal Lamb and our deliverance from evil/sin/darkness/slavery/bondage. The Israelites then, under the leadership of Moses, leave Egypt through the waters of the Red Sea into the desert. This event is indicated in the lower right side of the window.

The Passover Ritual Prescribed.

The LORD said to Moses and Aaron in the land of Egypt: This month will stand at the head of your calendar; you will reckon it the first month of the year. Tell the whole community of Israel: On the tenth of this month every family must procure for itself a lamb, one apiece for each household.
If a household is too small for a lamb, it along with its nearest neighbor will procure one, and apportion the lamb’s cost* in proportion to the number of persons, according to what each household consumes. Your lamb must be a year-old male and without blemish. You may take it from either the sheep or the goats.
You will keep it until the fourteenth day of this month, and then, with the whole community of Israel assembled, it will be slaughtered during the evening twilight. They will take some of its blood and apply it to the two doorposts and the lintel of the houses in which they eat it.
They will consume its meat that same night, eating it roasted with unleavened bread and bitter herbs. Do not eat any of it raw or even boiled in water, but roasted, with its head and shanks and inner organs. You must not keep any of it beyond the morning; whatever is left over in the morning must be burned up.
This is how you are to eat it: with your loins girt, sandals on your feet and your staff in hand, you will eat it in a hurry. It is the LORD’s Passover. For on this same night I will go through Egypt, striking down every firstborn in the land, human being and beast alike, and executing judgment on all the gods of Egypt—I, the LORD!
But for you the blood will mark the houses where you are. Seeing the blood, I will pass over you; thereby, when I strike the land of Egypt, no destructive blow will come upon you. This day will be a day of remembrance for you, which your future generations will celebrate with pilgrimage to the LORD; you will celebrate it as a statute forever.
For seven days you must eat unleavened bread. From the very first day you will have your houses clear of all leaven. For whoever eats leavened bread from the first day to the seventh will be cut off* from Israel. On the first day you will hold a sacred assembly, and likewise on the seventh.
On these days no sort of work shall be done, except to prepare the food that everyone needs. Keep, then, the custom of the unleavened bread,d since it was on this very day that I brought your armies out of the land of Egypt. You must observe this day throughout your generations as a statute forever.
From the evening of the fourteenth day of the first month until the evening of the twenty-first day of this month you will eat unleavened bread. For seven days no leaven may be found in your houses; for anyone, a resident alien or a native, who eats leavened food will be cut off from the community of Israel.
You shall eat nothing leavened; wherever you dwell you may eat only unleavened bread.

Promulgation of the Passover.

Moses summoned all the elders of Israel and said to them, “Go and procure lambs for your families, and slaughter the Passover victims. Then take a bunch of hyssop,* and dipping it in the blood that is in the basin, apply some of this blood to the lintel and the two doorposts. And none of you shall go outdoors until morning.
For when the LORD goes by to strike down the Egyptians, seeing the blood on the lintel and the two doorposts, the LORD will pass over that door and not let the destroyer come into your houses to strike you down. “You will keep this practice forever as a statute for yourselves and your descendants.
Thus, when you have entered the land which the LORD will give you as he promised, you must observe this rite. When your children ask you, ‘What does this rite of yours mean?’ you will reply, ‘It is the Passover sacrifice for the LORD, who passed over the houses of the Israelites in Egypt; when he struck down the Egyptians, he delivered our houses.’”
Then the people knelt and bowed down, and the Israelites went and did exactly as the LORD had commanded Moses and Aaron.