Exodus 12:43-51 - Institution Of The Passover
43 The Lord said to Moses and Aaron, “This is the statute of the Passover: no foreigner may eat it. 44 But any slave a man has purchased may eat it, after you have circumcised him. 45 A temporary resident or hired hand may not eat the Passover.
50 Then all the Israelites did this; they did just as the Lord had commanded Moses and Aaron. 51 On that same day the Lord brought the Israelites out of the land of Egypt according to their divisions.