Many things, but if one thing that we can point to is the idea of jewish supremacy. Yevamoth 98a says “non-jewish people are like donkey and cattle so they don’t have lineage.” Baba Mezia 114b says “non-jewish people are not man.” Iirc, logic in one of them went like: torah says you can visit the graves of men, and non-jews are filthy, therefore they must not be men (ie they must be animal). There’s another one that i remember reading from karl marx’s criticism of jewish community. Their scripture said don’t take ribat (interest, which was forbidden in islam and christianity too btw) from other people. They were like, non-jews are not people therefore the forbidence only apply to taking interest from jews. You can turn any commands about doing good to others in the scripture, into doing good only to jews, with this type of logic. I don’t think the original judaism preached about all this, hence there are many factions in judaism. Many of them are against palestinian genocide.