Exodus 12:43-51 - Institution Of The Passover
43 And the LORD said unto Moses and Aaron, "This is the manner of Passover: there shall no stranger eat thereof, 44 but all the servants that are bought for money shall ye circumcise, and then let them eat thereof. 45 A stranger and a hired servant shall not eat thereof. 46 In one house shall it be eaten. Ye shall carry none of the flesh out at the doors: moreover, see that ye break not a bone thereof. 47 All the multitude of the children of Israel shall observe it. 48 If a stranger dwell among you, and will hold Passover unto the LORD, let him circumcise all that be males, and then let him come and observe it, and be taken as one that is born in the land. No uncircumcised person shall eat thereof. 49 One manner of law shall be unto them that are born in the land, and unto the strangers that dwell among you."
50 And all the children of Israel did as the LORD commanded Moses and Aaron. 51 And even the self same day did the LORD bring the children of Israel out of the land of Egypt with their armies.