Can the one who cannot do either wudoo’ or tayammum offer supererogatory (naafil) prayers?
Question

What is the ruling on praying qiyaam al-layl for one who cannot do wudoo’ or tayammum by himself, and has no one to help him at that time of night? What is the ruling on offering supererogatory prayers for one who comes under the ruling on one who is unable to do either wudoo’ or tayammum, such as one who is paralysed and has no one to help him to do wudoo’ at that particular time?
Praise be to Allah.Prayer of one who is unable to do either wudoo’ or tayammum
The one who cannot find water or dust is called “the one who cannot do either way of purification.” The fuqaha’ differed concerning his prayer. Some of them said that he should not pray, which is the view of the Maalikis; some said that he may pray and should repeat it, which is the view of the Hanafis and Shaafa‘is; and some said that he may pray and he does not have to repeat it, which is the view of the Hanbalis.
The Shaafa‘is and Hanbalis stated that he should not offer supererogatory prayers.
It says in Mughni al-Muhtaaj (1/274): These three – namely the one who cannot find water or dust, the one who has some impurity on his body that he is afraid to wash off for some reason, and the one who is detained in an impure place – should offer the obligatory prayer only, because it is the time for the obligatory prayer, and they should not offer supererogatory prayers, because they are not necessary in this case. End quote.
It says in Kashshaaf al-Qinaa‘ (1/71): The one who has no access to water or dust, or is not able to use them because of some impediment, such as one who has ulcers on his skin and cannot let anything touch the skin in order to do wudoo’ or tayammum, should offer the obligatory prayer only, in whatever state he is in, because that is obligatory. That is because the Prophet (blessings and peace of Allah be upon him) said: “When I instruct you to do something, do as much of it as you can.” And because being unable to fulfil the condition does not mean that you should abandon the thing for which the condition was stipulated, such as being unable to have a sutrah (screen) in front of you whilst praying or being unable to face towards the qiblah.
And he does not have to repeat the prayer, because of the reports narrated from ‘Aa’ishah that she borrowed a necklace from Asma’ and lost it [whilst on a journey], so the Messenger of Allah (blessings and peace of Allah be upon him) sent some men to look for it, and they found it. Then the time for prayer came, and they did not have any water with them, so they prayed without wudoo’. They complained about that to the Prophet (blessings and peace of Allah be upon him), and Allah revealed the verse of tayammum. (Agreed upon.) and the Prophet (blessings and peace of Allah be upon him) did not instruct them to repeat the prayer, and because tayammum is one of the conditions of prayer, so it may be waived when it is not possible to do it, as is the case with all the conditions of prayer.
In this case, he should not do more than is sufficient for prayer to be valid. So he should not recite anything more than al-Faatihah, or say tasbeeh more than once, then he should not pause any longer than is required to be at ease when bowing, prostrating or sitting between the two prostrations. When he has finished reciting al-Faatihah, he should bow immediately, and when he has recited what is sufficient in the first tashahhud he should get up immediately, and when he has finished what is sufficient in the second tashahhud, he should say the tasleem immediately.
The one who has no access to water or dust and the like should not offer any supererogatory prayers, because it is only permitted for him to offer the obligatory prayer because it is necessary to do that. End quote.
See: al-Mawsoo‘ah al-Fiqhiyyah (32/191).
However, Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said that the person in this situation may offer supererogatory prayers.
He said: If someone cannot find water or dust, it is valid for him to do whatever he wants of obligatory or supererogatory prayers, and he may recite more than the bare minimum that is required." (Al-Fataawa al-Kubra  5/310).
Shaykh Muhammad ibn Ibraaheem Aal ash-Shaykh (may Allah have mercy on him) said in his Fataawa (2/87): He said, “If he is unable to find water or dust, he should offer the obligatory prayer only” because he is in a state of impurity, and he should not offer supererogatory prayers. This is what they meant.
What appears to be the case is that this view is not the more correct view, and the Shaykh (Ibn Taymiyah) favoured a different view. End quote.
According to the view of the Shaykh, you may pray qiyaam al-layl as you are, if you cannot find someone to help you do wudoo’ or tayammum.
And Allah knows best.