Israel has been in captivity in Egypt, Moses has completed his contests with Pharaoh, and the People of Israel have been expelled from Egypt. The death of Egyptian firstborn children and livestock has compelled their removal into the wilderness. At the end of Exodus 12, God institutes the Passover in remembrance of the Angel of Death passing by the homes of Jews on the night the Egyptian firstborn children were killed. Notably, they were spared if in a house with blood around the door. The Passover is established for Israel herself, including their slaves who have been circumcised. If a sojourner wants to celebrate the Passover with you, he can after he circumcises all males with him. I suspect that pretty much eliminated any visitors participating. In chapter 13, the protocols include redeeming Israel's firstborn. In this discussion, God says your firstborn belongs to God, and you must redeem your firstborn or you must kill it. God has redeemed Israel's firstborn by the blood...
Ramblings and observations