Is it better for a patient who is taking narcotic medications that cause him to lose consciousness and prevent him from performing prayers on time, to combine the five prayers after he wakes up and the effect of the medication wears off, and perform them completely with devotion, or to perform them on time with tayammum while sitting and without full consciousness?

It is not permissible to switch from ablution (Wudu') to Tayammum (dry ablution) except in the presence of a legitimate excuse, such as the unavailability of water, or the inability to use it due to illness. If an excuse is present, Tayammum is permissible; otherwise, it is not. The prayer of someone who performs Tayammum while able to use water is invalid.

If it becomes difficult to perform every prayer at its designated time due to illness, it is permissible to combine the Dhuhr and Asr prayers, and the Maghrib and Isha prayers, either by advancing or delaying them, while performing the Fajr prayer at its time. No other combinations are permissible.

Ablution with water is obligatory if it is available and can be used, even if the prayer time is short.

Do not pray when you do not comprehend what you are saying, for the Prophet, peace and blessings be upon him, said: «If one of you feels drowsy while praying, he should lie down until his sleep is gone, for if one of you prays while drowsy, he does not know; perhaps he intends to ask for forgiveness but ends up cursing himself.» If the prayer time is short, strive to comprehend what you say and do.