Vow of Peace( Book of Exalted Deeds, p. 48)
You have taken a sacred vow to abstain from harming any living creature.
Vow of Nonviolence (BE) ,
This sacred vow grants significant supernatural benefits, but its cost is high. First, you are constantly surrounded by a calming aura to a radius of 20 feet. Creatures within the aura must make a successful Will save (DC 10 + one-half your character level + your Cha modifier) or be affected as by the calm emotions spell. Creatures who leave the aura and reenter it receive new saving throws. A creature that makes a successful saving throw and remains in the aura is unaffected until it leaves the aura and reenters. The aura is a mind-affecting, supernatural compulsion. Second, you gain a +2 natural armor bonus to your AC, a +2 deflection bonus to your AC, and a +2 exalted bonus to your AC. This exalted bonus does not apply to touch attacks and does not hinder incorporeal touch attacks. Brilliant energy weapons, however, do not ignore it. It does not stack with an armor bonus. If you also have the Vow of Poverty feat, the natural armor, deflection, and exalted Armor Class bonuses granted by that feat all increase by +2. If a creature strikes you with a manufactured weapon, the weapon must immediately make a successful Fortitude save (DC 10 + one-half your character level + your Con modifier) or shatter against your skin, leaving you unharmed. Finally, you gain a +4 exalted bonus on all Diplomacy checks.
To fulfill your vow, you must not cause harm to any living creature (constructs and undead are not included in this prohibition). You may not deal real damage or ability damage to such creatures through spells or weapons, though you may deal nonlethal damage. You may not target them with death effects, disintegrate, or other spells that have the immediate potential to cause death or great harm. You also may not use nondamaging spells to incapacitate or weaken living foes so that your allies can kill them--if you incapacitate a foe, you must take him prisoner. If you intentionally break your vow, you immediately and irrevocably lose the benefit of this feat. You may not take another feat to replace it. If you break your vow as a result of magical compulsion or otherwise unwittingly, you lose the benefit of this feat until you perform a suitable penance and receive an atonement spell. (Characters who have taken a Vow of Peace are known to drink water through a strainer in order to avoid accidentally swallowing, and thereby causing harm to, a small insect.)