Tayammum

Tayammum (Arabic: تيمم) is the Islamic act of dry ritual purification using purified (clean) sand or stone or mud, which may be performed in place of ritual washing (wudu or ghusl) if no clean water is readily available or if one is suffering from moisture-induced skin inflammation or scaling or illness or hardship.

'[2] In Islamic law, Tayammum means to wipe the face and hands of a person with the purpose of purification for prayer by using soil, purified sand, or dust.

But if you are ill or on a journey, or any of you comes after 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.

And if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and find no water, then seek clean earth and wipe over your faces and your hands [with it].

The verse of tayammum was revealed while Muhammad was on an expedition with the Muslim army and accompanied alongside his wife Aisha.

The Hanafis, Shafi'is and a secondary opinion in the Maliki madhab says that wiping the hands till and including the elbows is fardh.

Tayammum is permitted on clean earth piece,[9] but the ideas about what is inside of this definition or not is depending per maddhabs.