Exodus 12:48-50

Amplified Bible

⁴⁸ If a stranger living temporarily among you wishes to celebrate the Passover to the Lord, all his males must be circumcised, and then he may participate and celebrate it like one that is born in the land. But no uncircumcised person may eat it. ⁴⁹ The same law shall apply to the native-born and to the stranger who lives temporarily among you.”

⁵⁰ Then all the Israelites did so; they did just as the Lord had commanded Moses and Aaron.