This is in the Bible?

No one whose testicles are crushed or whose penis is cut off shall be admitted to the assembly of the Lord.

 Those born of an illicit union shall not be admitted to the assembly of the Lord. Even to the tenth generation, none of their descendants shall be admitted to the assembly of the Lord.

 No Ammonite or Moabite shall be admitted to the assembly of the Lord. Even to the tenth generation, none of their descendants shall be admitted to the assembly of the Lord, because they did not meet you with food and water on your journey out of Egypt, and because they hired against you Balaam son of Beor, from Pethor of Mesopotamia, to curse you. (Yet the Lord your God refused to heed Balaam; the Lord your God turned the curse into a blessing for you, because the Lord your God loved you.) You shall never promote their welfare or their prosperity as long as you live. 

                                                                                    Deuteronomy 23: 1 - 6

I do not know how the Jewish people interpreted this passage of scripture during Jesus' time. I know that unlike our times, every Jewish male had memorized this passage along with the rest of the Pentateuch. This passage was not unfamiliar to them. I know that for "hardliners" the statement, No… Moabite shall be admitted to the assembly of the Lord – even to the tenth generation shall be admitted to the assembly of the Lord… You shall never promote their welfare or their prosperity as long as you live, must have been something of a problem scripture as they tried to reconcile it with the story of Ruth, the wonderful Moabite woman whose welfare was very directly promoted by the Jew, Boaz. And it was the third generation from her that David, the greatest king of Israel, the friend of God, was born.

We may think that whatever we read between the covers of the Bible has to be accepted in a completely straightforward way, but obviously, the writers of the Old Testament did not feel that way as can be seen in the story of Ruth. It appears to me from the way that scripture is sometimes understood in scripture itself that discernment is needed in the way that we understand the its authority. God revealed himself to Moses, spoke to Moses and Moses gave us God's words. But Jesus distinguishes at times between what God says and what Moses says. (See Mt. 19, It was because you were so hard-hearted that Moses allowed you to divorce your wives, but at the beginning it was not so. And I say to you, whoever divorces his wife, except for unchastity, and marries another commits adultery.) 

Understanding God's will can confuse us. But Jesus was not confused. He knew that this command in the Old Testament that said, You shall never promote their welfare or their prosperity as long as you live, was not meant to keep him from loving everyone, no matter their ethnicity, religious background, their appearance, or their customs. It wasn't meant to keep him from dying for them. What if we thought that everything in the Bible needed to be understood through Jesus and the two commands that Jesus gives us, to love God and to love our neighbors as ourselves? His love is the authority by which we understand what God’s will is.