Deuteronomy 23:2-3

2If someone was born when his parents were not properly married, he cannot join with the Lord's people. His descendants may not meet with the Lord's people to worship the Lord either. That will continue to the tenth generation of the man's descendants.

3Ammonite and Moabite people also cannot join with the Lord's people when they come together to worship him. Even the tenth generation of their descendants can never do this.