Thurs Sotah 10

The Gemara says that it's better to have yourself thrown into a furnace rather than embarrassing someone.

Tosfos points out that this is one of the three things for someone to go to gehenim without ever coming up.

Tosfos asks: why do we don't consider this as one of the Aveiros that one needs to give his life for?

Tosfos answers: we only count those sins that the Torah explicitly mentions. The Torah never explicitly expounded on the sin of embarrassing someone in public.