By the sun and its brightness

And the moon when it follows it

And the day when it displays it

And the night when it covers it

^{Surat al-Shams 1-4}

During the time of the prophet, as was also the case in the Hebrew world and in pre-Islamic Arabia, the day was not calculated as a twenty-four hour period starting at midnight (as our current system of time does). Rather, each day would marked at sunset, and would consist of two parts, starting with "Night" (ليل) and proceeding to "Day" (نهار).

The Qur'an itself does not define "night" clearly; while there are many references associating "day" with the sun and brightness and associating "night" with darkness and concealment, the exact delineation between the two is not so precise. In fact, according to the classical text الجامع لأحكام القرآن, Imam Qurtubi claims that God alone knows the exact measure of night, based on the revelation in Surat Al-Muzzammil that "Allah determines the night and the day" (الله يقدر الليل والنهار).

According to Lane's Lexicon, ليل and نهار are opposites, with no intervening period between them. Day, being defined as "the time from the rising of the dawn to sunset", would thus perfectly complement night, which would by extension be defined as the time from sunset to the rising of the dawn (i.e. sunset to Fajr). Similarly, Brill's Encyclopedia of the Qur'an considers the night to include everything from the "evening twilight" (شفق) until "the breaking of morning" (سحر), which immediately precedes the dawn (فلق) itself.

Surat al-Baqarah regulates the nights of fasting until "the white thread of dawn is distinct from the black thread" (يتبين لكم الخيط الأبيض من الخيط الأسود من الفجر), which correlates strongly with the above definitions.

It is important to note that, colloquially, the word ليل (night) can also be overloaded in a similar manner to the English "day", wherein it can be used to refer to an entire 24-hour period (more accurately, an entire period from sunset to sunset) rather than the night-time in particular. The intended meaning is usually clear in context, especially when ليل is used in a pluralized form, but this too needs to be kept in mind.

While there has been significant scholarly interest in the exact definitions of night and day, especially in regards to the transitory periods of twilight and dawn, much of this research was not conducted until significantly after the death of the prophet himself. As such, any references to "night" in the hadith literature were not necessarily (or likely) using the the term in any scientifically precise manner.

Yes, the Islamic day starts after Magrib.

Firstly: There is no report in the Prophet’s Sunnah to suggest that there are specific surahs or verses or adhkaar which, if the living recite them over the dead, they will have any effect such as making the deceased steadfast when he is questioned in al-barzakh, or that they will protect the deceased from the punishment of the grave. That which benefits the deceased most at that time, of actions on the part of the living, is their offering supplication (du‘aa’) for him and praying for forgiveness for him. There are a number of answers on our website which highlight the weakness of all the reports that have been narrated about the virtue of reciting Surah Yaa-Seen in particular. Some people believe that this surah has a particular effect in making things easier for the deceased in his grave, and they recite it over the grave after the burial, even though there is no proven report to support that in the Prophet’s Sunnah. Please see the following answers: 6460 , 82800 , 75894 and 72201 Secondly: According to Arab custom and Islamic teaching, the night belongs to the day that comes after it, not the day that comes before it. There is a great deal of evidence to support that, but the clearest evidence is what the people say on occasions of worship, such as the following: -1- Sighting the new moon of Ramadan, which indicates that the blessed month has begun. It may be noted that this night is regarded as part of Ramadan and the people pray Taraweeh on that night. -2- Sighting the new moon of Eid al-Fitr, which indicates that Ramadan has ended and the month of Shawwaal has begun. On that night the Muslims stop praying Taraweeh. When an Islamic text mentions the night of Friday, or the night of Eid, and so on, what is meant is the night according to the Islamic custom mentioned above. The same applies with regard to Laylat al-Qadr. There is a saheeh hadeeth which clearly indicates that the morning belongs to the night that comes before it. This is the hadeeth of Abu Sa‘eed al-Khudri (may Allah be pleased with him) according to which the Messenger of Allah (blessings and peace of Allah be upon him) used to observe i‘tikaaf during the middle ten days of Ramadan. He observed i‘tikaaf one year then, on the night of the twenty-first – which was the night on the morning of which he would come out of his i‘tikaaf – he said: ‘Whoever was observing i‘tikaaf with me, let him observe i‘tikaaf for the last ten days, for I was shown this night (Laylat al-Qadr), then I was caused to forget it. I saw myself prostrating in water and mud on the following morning (lit. on its morning). So seek it in the last ten days, and seek it on every odd-numbered night.” It rained that night, and the mosque was covered with palm branches and the mosque leaked, and my own eyes saw the Messenger of Allah (blessings and peace of Allah be upon him) with marks of water and mud on his forehead on the morning of the twenty-first. Narrated by al-Bukhaari (2027) and Muslim (1167) Think about the words “the night on the morning of which he would come out” and “on the morning of the twenty first”– this indicates that the morning belongs to the night that has just passed. Imam al-Qurtubi (may Allah have mercy on him) said, in his commentary on the verse in which Allah, may He be exalted, says (interpretation of the meaning): “And We appointed for Moosa (Moses) thirty nights and added (to the period) ten (more), and he completed the term, appointed by his Lord, of forty nights” [al-A ‘raaf 7:142]: The verse also indicates that the date starts with the night, not the day, because Allah, may He be exalted, says “thirty nights”. That is because the night is the beginning of the month. This is also how the Sahaabah (may Allah be pleased with them) spoke of days. It was narrated from them that they used to say: We fasted five with the Messenger of Allah. But the non-Arabs did it differently and based their counting on days, because their calendar was solar. End quote from al-Jaami‘ li Ahkaam al-Qur’an (7/267) Thirdly: Thus it is clear that if a person dies at 1 a.m. on Saturday, then according to Islamic custom he died on “the night of Saturday” and not on “Friday night.” So he is not included in the marfoo‘ hadeeth of ‘Abdullah ibn ‘Amr ibn ‘Aas, “There is no Muslim who dies on the day of Friday or the night of Friday but Allah will protect him from the trial of the grave.” Narrated by at-Tirmidhi (1074); classed as hasan by al-Albaani in Saheeh at-Tirmidhi However it should be noted that there is a difference of opinion among the scholars of hadeeth as to whether this hadeeth is saheeh or da‘eef. The majority are of the view that it is da‘eef. For more information on its isnaad, please see the following link: http://www.alukah.net/publications_Competitions/1008/38 And Allah knows best.

Witchcraft! (Just a joke. Relax)

I'm assuming you're asking about the morning and evening Atkhars. The best time to say the morning Atkhars is after Fajr prayer until sunrise. You can still say them up until noon (zenith noon, not 12 pm). The best time to say the evening Athkars is after Asr prayer until Maghrib. You can still say them up until you go to sleep for the night. According to Islam, the night period is between sunset and dawn. So essentially between Maghrib and Fajr times. You can pray Qiyam prayers anytime after you've prayed Isha until Fajr time. But the ideal window is in the last 3rd of the night period. The morning is between Fajr and the zenith (when the sun is at its highest point in the sky, local noon). You can pray the Duha prayer anytime between sunrise and the zenith.