Muslims enjoy the highest standard of personal hygiene of all the people in the world. In Islam, cleanliness and purification are not only requirements for the performance of worship, or when embracing Islam, but are part of a Muslim’s very faith. Allah says in the Qur’an: "Truly, Allah loves those who turn unto Him in repentance and loves those who purify themselves (by taking a bath and cleaning and washing thoroughly their private parts, bodies, for their prayers etc.)."(Al Baqarah: 222)
Cleanliness in Islam is of three kinds:
1- Purification from impurity (i.e. to attain purity or cleanliness, by taking a bath ghusl or performing ablution wudu’ in states in which a bath or ablution is necessary or desirable according to Islamic Law.
2- Cleansing one’s body, dress or place from an impurity of filth.
3- Removing the dirt or grime that collects in various parts of the body, such as cleaning the teeth and nostrils, the trimming of nails and the removing of armpit and pubic hair.
This is when all parts of the body are thoroughly washed. Ghusl is required of every Muslim after sexual intercourse, after wet dreams, after child-birth, and after post-partum bleeding (40-days flow of blood, and final yellowish discharge has completely stopped), and each month after menstruation and final yellowish discharge has stopped.
This simple ablution is necessary before prayer in the following cases:
1- after urinating or defecating;
2- if one breaks wind;
3- if one falls asleep lying down;
4- if one loses consciousness;
5- if one directly touches the genitals;
6- if one becomes excited, leading to a subsequent discharge.
The above cases also nullify one’s ablution, requiring a fresh one. Allah says in the Qur’an: "O you who believe! When you intend to offer prayer, wash your faces and your hands (forearms) up to the elbows, rub (by passing wet hands over) your heads, and (wash) your feet up to ankles. If you are in a state of Janaba, purify yourself (bathe your whole body)…." (Al-Ma’idah: 6)
Also on this issue, Abu Hurairah (may Allah be pleased with him) quoted Allah's Messenger (peace and blessings be upon him) as saying, "The prayer of a person who does hadath (passes, urine, stool or wind) is not accepted until he performs (repeats) the ablution." A person from Hadaramout asked Abu Hurairah, "What is 'hadath'?" Abu Hurairah replied, "'Hadath' means the passing of wind from the anus." (Sahih Al-Bukhari, Volume 1, Book 4, Number 137)
Merits of ablution:
Part of the merits of ablution is that it earns Muslims a special name by which they will be called on the Day of Judgment; the name is Al-Ghurr-ul-Muhajjalun (People of shinning bodily parts), due to performing ablution in proper way. Nu’aim Al-Mujmir reported: "Once I went up the roof of the mosque along with Abu Hurairah (may Allah be pleased with him). He performed ablution and said, ‘I heard the Prophet (peace and blessings be upon him) saying: On the Day of Resurrection, my followers will be called Al-Ghurr-ul-Muhajjalun from the traces of ablution and whoever can increase the area of his radiance should do so (by performing ablution in the most perfect manner.’" (Sahih Al-Bukhari, vol. 1, hadith No. 138)
Tayamum (Dry Ablution)
This is performed by putting or striking lightly the hands over clean earth and then pass the palm of each on the back of the other, blow off the dust then pass them on the face. It is performed instead of wudu and ghusl (in case of ritual impurity, etc.). Allah says in the Qur’an: "… But if you are ill or on a journey or any of you comes from answering the call of nature, or you have been in contact with women (i.e., sexual intercourse) and you find no water, then perform tayammum with clean earth and rub therewith your faces and hands. Allah does not want to place you in difficulty, but He wants to purify you, and to complete His Favor on you that you may be thankful." (Al-Ma’idah: 6)
To illustrate the importance of Muslims maintaining their high level of personal hygiene, the following points are specifically mentioned by Prophet Muhammad (peace and blessings be upon him) on answering the call of nature.
`A’ishah, the Mother of the Faithful (may Allah be pleased with her): "The Prophet (peace and blessings be upon him) used his right hand for getting water for ablution and taking food, and his left hand for his evacuation and for anything repugnant." (Sunan Abu Dawud)
Abu Hurairah (may Allah be pleased with him) reported: "The Messenger of Allah (peace and blessings be upon him) said: ‘Be on your guard against two things which provoke cursing.’ They (the Companions present there) said: ‘Messenger of Allah, what are those things which provoke cursing?’ He said: ‘Easing on the thoroughfares or under the shades (where people take shelter and rest).’” (Reported by Muslim)
ReF:http://www.islamawareness.net/Cleanliness/personal.html