Tahaarah means purity, but Islamically it refers to a state of cleanliness in order to perform certain acts of worship. By entering into a state of purity, a Muslim prepares himself physically and spiritually to worship Allah subhana wa ta'ala.

Rasulullah sallallahu alayhi wa sallam said "Prayer is not accepted from one who breaks his state of tahaarah until he makes wudoo." [al bukhari] Thus, if any of the following have taken place, we are forbidden from performing the prayer until we regain proper state of Tahaarah.

1. Passing Gas: Abbad ibn Tameem said "My uncle asked rasulullah sallallahu alayhi wa sallam about a person who imagined that he passed gas during his prayer. Rasulullah sallallahu alayhi wa sallam said "He should not leave his prayer unless he hears a sound or smells something."

2. Urinating

3. Defecating

Allah subhana wa ta'ala said in the Qur'an "..or if one of you comes from relieving himself." [4:43]

4. Deep Sleep: In the case where one sleeps sitting upright deep sleep does not break tahaarah. "The prophet's companions used to wait for the night prayer until their heads would nod, then get up and perform prayer without making wudoo." [reported by Anas, Sahih Muslim, at tirmidhi, sunan abu dawud]

Ali bin abi Talib radi Allahu anhu said that rasulullah sallallahu alayhi wa sallam said "The eye is the drawstring of the anus, so whoever sleeps should make wudoo." [abu dawud, ibn majah, ad daraqatni/ hasan]

5. Touching Private Parts: Abu Hurairah radi Allahu anhu said that he heard rasulullah sallallahu alayhi wa sallam say "Whoever touches his private with is hand without any covering between them must make wudoo." [ahmad,al haakim, al baihaqi, ad daraqutni, ibn hibban/sahih]

There are many hadiths that say touching private parts breaks wudoo, and others that say touching private parts will not break wudoo. For instance, an older man came to rasulullah sallallahu alayhi wa sallam to ask him if it breaks his wudo and rasulullah's [sallallahu alayhi wa sallam] answer was "Is it only part of you?" By this he was asking if touching it was like touching any other part of the body. Thus, the scholars have said that if the private part is touched with sexual desire or sexual arousal of any means the hadiths that say it breaks the wudo apply. If, however, the private part was not touched with sexual desire or sexual arousal it does not break the wudoo.

In the case of vomiting, there are no strong hadiths that serve as proof that vomiting breaks wudoo. The hadith attributed to 'A'isha radi Allahu anhu saying that "Whoever is afflicted by Qay, Ru'aaf or qals should leave [prayer], make wudoo, then continue where he left off without speaking during it." is a da'eef hadith [al albaani da'eef al jami'i as sagheer].

The only authentic hadith is related by Abu Darda collected by Imam Ahmad and at Tirmidhi. However, this tradition only indicates the Prophet's sunnah and does not indicate that wudoo is necessary in the case of vomiting.

In the case of blood, aside from the woman's mense, there are no authentic hadiths wherein in wudoo is required. In fact, Imam al Bukhari quoted Jaabir in Abdillah as saying "Rasulullah sallallahu alayhi wa salam was in the battle of Dhaat arRuqaa' and a person who was shot with an arrow bled profusely, but he bowed and prostrated continuing his prayer." He also quoted Hussayn ibn Ali bin Abi Talib as saying "The Muslim used to pray despite their wounds." and said that Ibn Umar squeezed on of his pimples and blood came out but he did not repeat his wudoo. [bukhari 1/35]