The Passover

Exodus 12:11,48  

11. And thus shall ye eat it; with your loins girded, your shoes on your feet; and your staff in your hand; and ye shall eat it in haste; it is the Lord’s passover.   

48. And when a stranger shall sojourn with thee, and will keep the passover to the Lord, let all his males be circumcised, and then let him come near and keep it; and he shall be as one that is born in the land: for no un circumcised person shall eat thereof.