Cure wounds

Cure light wounds is a widespread conjuration spell that heals small injuries.

Effect
When laying your hand upon a living creature, you channel positive energy that cures 1d8 points of damage +1 point per caster level (up to +5).

Since undead are powered by negative energy, this spell deals damage to them instead of curing their wounds. An undead creature can attempt a Will save to take half damage.

Sourcebooks
3rd edition 4th edition