You have taken a sacred vow to forswear material possessions.
Prerequisites: Sacred Vow.
Benefit: You gain bonuses to your Armour Class, ability scores, and saving throws, as well as bonus exalted feats, all depending on your character level. The level at which the character swears the vow (and takes the appropriate feats) is irrelevant; if he gives up his possessions at 10th level he gains all the benefits of a 10th-level ascetic character, with the exception of bonus exalted feats.
AC Bonus (Su): A 1st-level ascetic receives a +4 exalted bonus to his Armour Class. The bonus increases to +5 at 3rd level, and thereafter increases by +1 for each 3 character levels. This bonus does not apply to touch attacks and does not hinder incorporeal touch attacks. Brilliant energy weapons, however, do not ignore this bonus. This does not stack with an armour bonus.
Bonus Exalted Feats: At 1st level, an ascetic gets a bonus exalted feat, and another bonus feat at 2nd level and every 2 levels thereafter. Unlike the other benefits of a vow of poverty, a character does not gain these bonus feats retroactively when he takes the Vow of Poverty feat; he only gains those bonus feats that apply for the levels he gains after swearing his vow. Thus, the bonus feat gained at 1st level is available only to humans who take both Sacred Vow and Vow of Poverty at 1st level.
Endure Elements (Ex): A 3rd-level ascetic is immune to the effects of being in a hot or cold environment. He can exist comfortably in conditions between -50 and 140 °Fahrenheit (-45 and 60 °Celsius) without having to make Fortitude saves (as described in the Dungeon Master’s Guide).
Exalted Strike (Su): At 4th level, an ascetic gains a +1 enhancement bonus on all his attack and damage rolls. In effect, any weapon the character wields becomes a +1 magic weapon, and can overcome the damage reduction of a creature as though it were a magic weapon. This enhancement bonus rises to +2 at 10th level, to +3 at 14th level, to +4 at 17th level, and to +5 at 20th level. At 10th level, any weapon damage the character deals is also considered to be good-aligned, so that it can bypass the damage reduction of some evil outsiders.
Sustenance (Ex): A 5th-level ascetic doesn’t need to eat or drink.
Deflection (Su): A 6th-level ascetic receives a +1 deflection bonus to his Armour Class. This bonus increases to +2 at 12th level, and to +3 at 18th level.
Resistance (Ex): At 7th level, an ascetic gains a +1 resistance bonus on all saving throws. This bonus increases to +2 at 13th level, and to +3 at 17th level.
Ability Score Enhancement (Ex): At 7th level, an ascetic gains a +2 enhancement bonus to one ability score. At 11th level, he gains an extra +2 bonus to that score, and a +2 bonus to another ability score. At 15th level, he gains an extra +2 bonus to those two scores, and a +2 bonus to a third ability score. At 19th level, he gains an extra +2 bonus to those three scores, and a +2 bonus to a fourth ability score.
Natural Armour (Ex): At 8th level, an ascetic gains a +1 natural armour bonus, or his existing natural armour bonus increases by +1. It increases an extra +1 at 16th level.
Mind Shielding (Ex): Also at 8th level, an ascetic character becomes immune to detect thoughts, discern lies and any attempt to discern his alignment.
Damage Reduction (Su): An ascetic gains damage reduction 5/magic at 10th level. At 15th level, this improves to 5/evil, and at 19th level to 10/evil.
Greater Sustenance (Ex): Once he attains 12th level, an ascetic character doesn’t need to breathe.
Energy Resistance (Ex): At 13th level, an ascetic gains resistance 5 to acid, cold, electricity, fire, and sonic energy. At 20th level, this increases to resistance 15.
Freedom of Movement (Ex): At 14th level, an ascetic can act as if continually under the effect of a freedom of movement spell.
Regeneration (Ex): At 17th level, an ascetic heals 1 point of damage per level every hour rather than every day. (This ability cannot be aided by the Heal skill.) Non-lethal damage heals at a rate of 1 point of damage per level every 5 minutes.
True Seeing (Su): At 18th level, an ascetic gains a continuous true seeing ability, as the spell.
Special: To fulfill your vow, you must not own or use any material possessions, with the following exceptions: You may carry and use ordinary (neither magic nor masterwork) simple weapons, usually just a quarterstaff that serves as a walking stick. You may wear simple clothes (usually just a homespun robe, possibly also including a hat and sandals) with no magical properties. You may carry enough food to sustain you for one day in a simple (non-magic) sack or bag. You may carry and use a spell component pouch.
You may not use any magic item of any sort, though you can benefit from magic items used on your behalf — you can drink a potion of cure serious wounds a friend gives you, receive a spell cast from a wand, scroll or staff, or ride on your companion’s ebony fly. You may not, however, “borrow” a cloak of resistance or any other magic item from a companion for even a single round, nor may you yourself cast a spell from a scroll, wand or staff.
If you break your vow, you immediately and irrevocably lose the benefit of this feat. You may not take another feat to replace it.
Source: Book of Exalted Deeds (Page 48)