Is a prisoner who finds neither water nor earth permitted to wipe over the walls in order to perform Tayammum (dry ablution)? Or is Tayammum valid only with earth?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

A prisoner who cannot obtain water to perform Wudhoo’ (ablution) is required to exert his utmost to get it from the prison warden or through any other legitimate means. When having exerted his utmost and still unable to obtain water, he is permitted to perform Tayammum. Allaah Almighty says (what means): {O you who have believed, do not approach prayer while you are intoxicated until you know what you are saying or in a state of Janaabah, except those passing through [a place of prayer], until you have washed [your whole body]. 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]. Indeed, Allaah is ever pardoning and forgiving.} [Quran 4: 43]

The Hanbali and Shaafi‘i scholars said that Tayammum is permitted with dust only. The Maaliki and Hanafi scholars are of the view that Tayammum is permitted with everything of which the source is earth. In Al-Mughni, Ibn Qudaamah said: "Maalik and Abu Haneefah said that Tayammum is permitted with everything of which the source is earth, such as mortar, arsenic and stones. Al-Awza‘i said that sand belongs to the earth."

Hammad ibn Abi Sulayman said: "It is permissible to perform Tayammum with marble, as it is narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said, 'Earth has been made a place for prayer and a means of purification for me.' [Al-Bukhari]"

Consequently, it is permissible to perform Tayammum with the wall if it is made of something that belongs to the earth, according to the Maaliki and Hanafi scholars . If the wall is made from something other than the earth for example or one does not find something to perform Tayammum therewith, he is permitted to pray with neither Wudhoo’ nor Tayammum and he is not required to repeat these prayers later. Allaah Almighty says (what means): {So fear Allaah as much as you are able and listen and obey and spend [in the way of Allaah]; it is better for your selves. And whoever is protected from the stinginess of his soul – it is those who will be the successful.} [Quran 64: 16]  

Allaah Knows best.