You have heard that it was said, 'You shall love your neighbor and hate your enemy.' (Matthew 5:43)
This is in fact what the Jewish teachers had done. Using logic they reasoned that if we are to love our neighbor then there is a category of not neighbor that should get not love.
But God hadn't actually said anything about not neighbors and so the teachers were committing the negative inference fallacy to supply the missing piece. The reason God didn't say anything about not neighbor was because the positive category of neighbor was intended to cover everyone, which is why He answered the lawyers question with the parable of the Good Samaritan.
Today some people think that because Jesus says He lays down His life for His sheep that there's a category of not sheep who Jesus did not lay down His life for. Or because He says He loves His elect that there's the category of not-elect who get nothing but not-love. This is not only bad reasoning, it's reasoning openly condemned by Jesus in the sermon on the mount.