Anesthesia itself does not break the fast because anesthetic gases have no physical substance (jirm), and subcutaneous anesthesia injections do not reach the body cavity (jauf). However, this is on condition that the person is conscious at some point during the fasting hours:

● If they were awake at the beginning of the day, their fast remains valid.

● If they wake up even for a moment before sunset, their fast is also valid.

However, if the surgery involves the entry of foreign substances into the body cavity, their fast is invalidated, and they must make up for that day later.

All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.

The time for night prayer (qiyām al-layl) begins after the Maghrib prayer and lasts until the second adhān of Fajr. The best time for it is the last third of the night, and best of all are the fourth and fifth sixths of the night. If the night is divided into two halves, the latter half is better.

Whoever intends to pray at night is encouraged to delay the Witr until he has prayed the night prayer. If he knows that he will not wake up, it is better for him to pray and perform Witr before sleeping, so that he does not miss both the night prayer and the Witr.

It is stated in Mughnī al-Muḥtāj (Vpl.1/p.462): “I say: The voluntary prayer of the night, that is, the absolute voluntary prayer (al-nafl al-muṭlaq), is better than the absolute voluntary prayer of the day, because of the report in Muslim: ‘The best prayer after the obligatory prayer is the night prayer.’ In another narration of his: ‘In the night there is an hour that no Muslim man meets while asking Allah for any good of this world and the next except that He gives it to him, and that is every night.’ It is also because the night is a time of heedlessness. I restricted the voluntary prayer to the absolute kind following the commentator, although what the ḥadīth and the underlying meaning require is that the night rawātib be preferred over the day rawātib, since the jurists preferred the two rakʿahs of Fajr over everything except Witr. The middle of the night is better than its two ends if it is divided into thirds, because heedlessness is greatest then and worship is hardest. If he wishes to pray during some third, the best is the fourth and fifth sixths, based on the ḥadīth in the two Ṣaḥīḥs: ‘The most beloved prayer to Allah the Exalted is the prayer of Dāwūd: he would sleep half the night, stand for a third of it, and sleep for a sixth.’ Then the latter part is better than the first if he divides it into two halves, because of the saying of Allah the Exalted: ‘And in the hours before dawn they would ask forgiveness’ [al-Dhāriyāt: 18], and the report of the two Shaykhs: ‘Our Lord, Blessed and Exalted, descends,’ meaning His command descends, ‘to the lowest heaven when the last third of the night remains, and says: Who calls upon Me, that I may answer him? Who asks of Me, that I may give him? Who seeks My forgiveness, that I may forgive him?’”

It is also stated in ʿUmdat al-Sālik (p. 60): “It is better to perform it [the Witr] immediately after the sunnah of ʿIshāʾ, unless he has tahajjud, in which case it is better to delay it so that he performs Witr after it. If he performs Witr and then wishes to pray tahajjud, he prays two rakʿahs at a time and does not repeat the Witr, nor does he need to cancel it with a single rakʿah before the tahajjud. It is recommended that he not deliberately pray after it.”

Qiyām al-layl is a term applied to any prayer performed at night. Tahajjud, on the other hand, refers to the night prayer that follows sleep, whether it is prayed after Maghrib or after ʿIshāʾ, or the prayer performed after ʿIshāʾ without sleep. On this basis, the Witr is also called tahajjud, since it is only prayed after ʿIshāʾ.

It is stated in al-Majmūʿ (Vol.4/p.84): “The sound position, as stated in al-Umm and al-Mukhtaṣar, is that the Witr is called tahajjud.”

It is stated in Nihāyat al-Zayn (Vol.1/p.114): “Among the absolute voluntary prayers is qiyām al-layl. If it is performed after sleep, even during the time of Maghrib and after having prayed ʿIshāʾ early (taqdīman), it is called tahajjud.”

And it is stated in Ḥāshiyat al-Bujayrimī ʿalā al-Khaṭīb (Vol.1/p.418): “His statement: ‘(the night prayer)’: the genitive construction (iḍāfah) carries the sense of fī, meaning a prayer in the night. His statement: ‘(it would be more fitting)’: the reason it is more fitting is that the night prayer includes both tahajjud and other prayers.” And Allah Almighty knows best.