Exodus 12:13
The blood shall be to you for a token on the houses where you are. When I see the blood, I will pass over you, and no plague will be on you to destroy you when I strike the land of Egypt.
World English Bible (Public Domain)
In context
Before · Exodus 12:11–12
11This is how you shall eat it: with your belt on your waist, your sandals on your feet, and your staff in your hand; and you shall eat it in haste: it is the LORD’s Passover. 12For I will go through the land of Egypt in that night, and will strike all the firstborn in the land of Egypt, both man and animal. I will execute judgments against all the gods of Egypt. I am the LORD.
13The blood shall be to you for a token on the houses where you are. When I see the blood, I will pass over you, and no plague will be on you to destroy you when I strike the land of Egypt.
After · Exodus 12:14–15
14This day shall be a memorial for you. You shall keep it as a feast to the LORD. You shall keep it as a feast throughout your generations by an ordinance forever. 15“‘Seven days you shall eat unleavened bread; even the first day you shall put away yeast out of your houses, for whoever eats leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.