What does Exodus 12:43 mean?

Israel was freed from Egyptian slavery through powerful, devastating plagues on Egypt (Exodus 12:29–33). The last of these, known as Passover (Exodus 12:12–13), is to become a permanent, annual celebration. The Lord provided instructions for the initial observance (Exodus 12:1–20). This is a central event establishing the identity of the nation of Israel. Those barred from the celebration are identified by the Hebrew phrase ben nēkār. This literally means "son of a stranger." This verse might seem restrictive, but it is part of a very inclusive concept of God's chosen people (Deuteronomy 14:2).

When Israel left Egypt, many non-Israelites joined them (Exodus 12:38). These were probably Egyptians who recognized the Lord's power (Exodus 8:18–19; 10:7). God's distinction between Israelites and non-Israelites had ethnic components, but it was primarily a matter of faith. Those not born naturally into the nation could join it through their belief and obedience. Those who accepted the Hebrew concept of circumcision (Genesis 17:10–14) were part of that covenant. The "foreigner" mentioned here is someone who is not part of this community. Those who wanted it could participate (Exodus 12:48) if they followed the covenant.