So listen now to what the Gemara (ibid.) says about this: The sin of hurtful words is worse than the sin of cheating a man out of his money. It means that the nice crook on this side of the street is better – because he’s only cheating you out of your money; but at least he’s not hurting your feelings. And who’s the bigger crook? The honest grocer who would never take a penny from you.
So here’s a nice Jewish boy who would never even dream about stealing from his mother – a son wouldn’t sin against his mother like that. But suppose his mother is talking up a storm so he pipes up, “Ma, don’t talk so much.” Ooooh! He’s hurting his mother’s feelings! That’s worse than sneaking into her room when she’s out and stealing money from her pocketbook! Hurtful words are worse than geneivah.