Whoever is able to do wudu – even if it is difficult but bearable – it is not permissible for him to do tayammum
Question

I had an accident at work and fell from the fourth floor, and I broke my back and my right ankle, for which I have undergone two operations. I am well now – praise be to Allah – and I walk with one cane. There is some mild pain only, but I have to pray lying on my back until I recover fully, and I do tayammum for some prayers, and wudu for others. Especially in the case of Fajr prayer, I do not get up to do wudu; I do tayammum only, because I have to get up to go to the sink, and take the chair with me, then do wudu and come back to my bed to pray. Is what I am doing permissible, because I think that in my situation, tayammum is easier than wudu; am I excused for that? Please note that I do wudu sometimes and tayammum sometimes.
Praise be to Allah.The one who is sick must use water to purify himself, as is required of one who is healthy. If he is unable to do wudu by himself, someone else may help him to do wudu. If he is not able to do wudu and cannot find someone to help him to do it, then he must do tayammum.
See the answers to questions no. 104172 and 106758.
If someone has water available and is able to use it to purify himself, he must use it, and it is not permissible for him to do tayammum unless he has an excuse.
Ash-Shirazi (may Allah have mercy on him) said:
It is not permissible to do tayammum after the time for a prayer has begun, except for one who has no access to water or is afraid to use it. As for the one who has access to water, it is not permissible for him to do tayammum, because the Prophet (blessings and peace of Allah be upon him) said: “Clean earth is a means of purification for the Muslim if he cannot find water.”
End quote from al-Muhadhdhab, 1/69.
Ibn Qudamah (may Allah have mercy on him) said:
The Prophet’s words – “Clean earth is a means of purification for the Muslim even if he cannot find water for ten years, but when water becomes available, use it to wash yourself” – imply that clean earth is not a means of purification when water is available, and explicitly state that water is what must be used when it is available.
End quote from al-Kafi, 1/128.
The scholars of the Permanent Committee for Ifta’ said:
The basic principle is that purification must be done with water if it is available and one is able to use it… In the case of one who does tayammum when he is able to use water, his prayer is not valid.
End quote from Fatawa al-Lajnah ad-Da’imah, 4/186.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) said:
If you are not able to use water, do tayammum, and even if you continue to pray with tayammum for a long time, there is nothing wrong with that, so long as the condition for doing so remains, which is not being able to use water.
End quote from Majmu` Fatawa wa Rasa’il al-`Uthaymin, 11/238.
He also said:
If someone is able to use water, it is not permissible for him to do tayammum, because Allah, may He be Exalted, says (interpretation of the meaning): {… and do not find water …} [al-Ma’idah 5:6].
End quote from Fatawa Nur `ala ad-Darb, 7/2.
Based on that, if you are able to do wudu, even with some difficulty, but it is a normal level of difficulty that you can put up with and it will not cause severe pain, or a delay in healing, or exacerbate the sickness, then you must use water and do wudu, and it is not permissible for you to do tayammum in this case.
But if the difficulty is extreme or will lead to other things as mentioned above (exacerbation of sickness or delay in healing), then it is permissible for you to do tayammum in that case.
Thirdly:
If doing wudu is too difficult for you, then Allah, may He be Exalted, has reduced the burden for one who is sick and has permitted him to put together Zuhr and `Asr, and Maghrib and `Isha’. So you can do one wudu and pray Zuhr and `Asr together at the time of the earlier or later prayer, whichever is easier for you. And you can do the same for Maghrib and `Isha’.
For more information, see the answer to question no. 97844.
We ask Allah, may He be Exalted, to grant you healing and well-being.
And Allah knows best.