Praise be to Allaah.

Prayer is obligatory for the Muslim whatever state he is in, so long as he remains of sound mind. If a person is sick but is able to pray standing, then he should pray standing; if he cannot, then he should pray sitting; if he is unable to do that, then he should pray lying on his side; if he cannot do that then he should pray lying on his back, because of the report narrated by al-Bukhaari (1066) from ‘Imraan ibn Husayn, who said: I had haemorrhoids, so I asked the Prophet (blessings and peace of Allah be upon him) and he said: “Pray standing, and if you cannot, then (pray) sitting, and if you cannot then (pray) on your side.” The ruling concerning purification is similar. If he is able to do wudoo’ with water, then he should do that; if he cannot do that, then he should do tayammum, using dust. 

Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him) was asked about the patient who has a catheter: how should he pray and how should he do wudoo’? 

He replied: He should pray according to his situation, like the one who is incontinent and like the woman who is suffering from istihaadah (non-menstrual vaginal bleeding). The sick person should pray according to his situation when the time of the prayer begins. He should do tayammum if he is unable to use water, but if he is able to do that then he must do wudoo’ with water, because Allah says (interpretation of the meaning): 

“So keep your duty to Allaah and fear Him as much as you can”

[al-Taghaabun 64:16].

And anything that comes out after that will not matter, but he should not do wudoo’ until the time for that prayer begins, and he may pray regardless of anything that comes out, so long as it is within the time of that prayer, even if urine is coming out of his penis; the same applies to the woman who is suffering from istihaadah: she may pray within the time of the prayer, even if it comes out of her for a long time. So she should pray according to her situation. But the one whose condition means that he is continually breaking his wudoo’ should not do wudoo’ until the time for it begins, because the Prophet (blessings and peace of Allah be upon him) said to the woman who was suffering istihaadah: “Do wudoo’ at the time for every prayer.” So the one who is incontinent, the woman who is suffering istihaadah and the patient asked about here may offer prayers at the time for every prayer, both obligatory and naafil, read Qur’aan from the Mushaf and circumambulate the Ka‘bah (tawaaf), if they are in Makkah at that time. But when the time for that prayer ends, they should refrain from these actions until they have done wudoo’ for the prayer whose time has now begun. End quote. 

Al-Fataawa al-Muta‘alliqah bi’l-Tibb wa Ahkaam al-Marda (p.34). 

And Allah knows best.