On being nicer than you think you should be:

You’ve heard that it was said, "An eye in place of an eye, and a tooth in place of a tooth." But I tell you, don’t oppose someone who is evil. Whoever slaps you on the right cheek, turn the other cheek to him as well; and to whoever wants to get a judgment against you and takes your shirt, give him your coat too; and if someone forces you to go one mile, go with him two.

(Matthew 5:38-41)

On self-superiority bias:

Why do you look at the speck that’s in your brother’s eye, and don’t notice the plank that’s in your own eye?

(Matthew 7:3)

I disagree with Will's interpretation that the former follows from the latter.