Albert Barnes Commentary Exodus 12:19

"Seven days shall there be no leaven found in your houses: for whosoever eateth that which is leavened, that soul shall be cut off from the congregation of Israel, whether he be a sojourner, or one that is born in the land." — Exodus 12:19 (ASV)

Born in the land - A stranger or foreigner might be born in the land, but the word here used means “a native of the land,” belonging to the country by virtue of descent, that descent being reckoned from Abraham, to whom Canaan was promised as a perpetual inheritance.