And the LORD said to Moses and Aaron, “This is the statute of the Passover: No foreigner is to eat of it.
43. This is the ordinance of the passover. Since the passover was the sacred bond whereby God would hold the elect people in obligation to Himself, He forbids all strangers from partaking of it; because a promiscuous permission to eat of it would have been an unworthy profanation.
Some further precepts are here given concerning the passover, as it should be observed in times to come. I. All the congregation of Israel must keep it, Exo 12:47. All that share in God's mercies should join in thankful praises for them. Though it was observed in families apart, yet it is looked upon as the act of the whole congregation; for the smaller communities constituted the greater.
Commenting on Exodus 12:43-51
A foreigner and an hired servant shall not eat thereof. One of another nation, and one that was only hired by the day, week, or year; as they were not obliged to circumcision, so without it they had no right to eat of the passover, none but such as became proselytes of righteousness. A foreigner and an hired servant shall not eat thereof.