What does Exodus 12:9 mean?
Israel is about to leave Egypt in a great rush (Exodus 12:29–33). The people are to eat this meal prepared for travel (Exodus 12:11). Keeping the head, legs, and entrails with the lamb during cooking would have been unusual, but also much quicker than fully butchering it. Most scholars assume that parts such as the intestines would have been removed, since leaving feces in the meat would contaminate the entire meal. Other organs, such as lungs, liver, and heart were to be kept. The limbs were not to be removed; the animal was to be roasted as "whole" as possible.Roasting was the only proper way to prepare the designated sacrificial lambs (Exodus 12:5–6) for eating. This verse emphasizes that the cooking method mattered. The lambs are symbolic of the death of the Messiah; a role which would later be fulfilled through Jesus Christ (John 1:29; 1 Corinthians 5:7). Every bit of the lamb was to be consumed (Exodus 12:10), and boiling would disperse some of the flesh into the water.
Exodus 12:1–28 records the Lord's instructions for the first observation of Passover. The Israelites are to sacrifice lambs and prepare a specific set of foods. These must be eaten while dressed for travel. The lamb's blood is to be collected at the threshold of the door and then applied to the top and side posts. On that first Passover, God will kill the firstborn of Egypt (Exodus 11:4–6). Houses marked with the lamb's blood will be spared: God's judgment will "pass over" them without harm (Exodus 11:7). This event will establish a new start for Israel's yearly calendar. It is to be commemorated every year by using various symbolic elements. Future generations are to be carefully taught the meaning of these things.
Israel is to realign their calendar to begin with the current month. They receive instructions to prepare a special meal. This includes sacrificing lambs and applying their blood to the doorway of each home. Following these instructions will cause God's wrath to "pass over" that house. Egypt's firstborn are killed and they demand Israel leave immediately. The people quickly gather their belongings and march out in a single massive group. These events are to be remembered with festivals to be celebrated for all time.