Musar על אבות 3:11

Never humiliate anyone in public for one who does so has no portion in the World to Come.

The third category of gossip is he who, in the presence of others, shames another because of something which his ancestors did. Concerning this our Sages, of blessed memory, said, "Everyone who causes the face of his companion to whiten (through shame) in public has no share in the world to come" (Aboth, 3:11).