Is tayammum (dry ablution with clean earth) permissible for one who is unable to perform ghusl (the full ritual bath)?

Question:
The questioner: I am a sick man and I am unable to perform the full ritual bath, so I was told to perform tayammum (dry ablution with clean earth). I performed tayammum with dust. My question is: does this tayammum cover every obligatory prayer, or is wudu' (the ablution for prayer) sufficient for me? And if my body recovers, I will perform the full ritual bath, if Allah wills.

Answer:
One who is unable to perform wudu' (the ablution for prayer) due to illness or fainting should perform tayammum (dry ablution with clean earth). If his illness prevents him from using water because the water would harm him, he performs tayammum. He strikes the earth with his hands once, then wipes his face and his palms. If he does this for the Fajr (dawn prayer) and remains in a state of purity, he prays with it until 'Asr (the afternoon prayer) according to the correct view. Or if he does it for 'Asr and remains in a state of purity, he prays with it until Maghrib (the sunset prayer). Tayammum is like water; it is a purifier like water, as the Prophet (peace and blessings be upon him) said: "The dust is your mosque and your purifier." The correct view is that it remains valid for you until water is found or the excuse is removed.