Some people say it is in the Talmud or other Orthodox Jewish texts but how do I really know enemies of Jews are not making it up

It is on websites that say they are run by Jews or Jewish organizations that people claiming to be Jews who you could talk to at synagogues would claim are Jewish websites

Like for example the Chabad Jewish denomination has a website

If you went to a Chabad synagogue and asked if that is a Chabad website

Either they should say yes or they could be suing the website