Exodus 12:13

13 The blood will be a sign for you on the houses where you are, and when I see the blood, I will pass over you. No destructive plague will touch you when I strike Egypt.

Read Exodus 12:13 Using Other Translations

And the blood shall be to you for a token upon the houses where ye are: and when I see the blood, I will pass over you, and the plague shall not be upon you to destroy you, when I smite the land of Egypt.
The blood shall be a sign for you, on the houses where you are. And when I see the blood, I will pass over you, and no plague will befall you to destroy you, when I strike the land of Egypt.
But the blood on your doorposts will serve as a sign, marking the houses where you are staying. When I see the blood, I will pass over you. This plague of death will not touch you when I strike the land of Egypt.