Sahoor, also spelt as Sahur or known in Urdu as
sehri, is the name for the pre-Dawn meal before fasting during the month of
Ramadan.
Iftar is the meal after sunset, to break the
fast.
If a Muslim is fasting that day, he or she usually wakes up before dawn and eats a light meal, known as a "Sahoor." During Ramadan, the whole family wakes up and has a quick, short breakfast, usually eating quietly or with less fanfare than usual. It's not usually a large or heavy meal, nor is it intended to stuff oneself.
The Sahoor has two practical purposes. First, if you are going to fast, getting a quick bite before you start is a good way to delay hunger pangs. Also, the Prophet Muhammad (pbuh) commanded the Muslims to take the Sahoor as a means of being different in their fasting from the fasting of the People of the Book (ie. the Christians and Jews). Typically among Christians and Jews, a person would begin the fast as soon as he or she slept the night before (and Catholics observed the same for Communion up until relatively recently). Very early on, the Muslims followed that example until commanded to by a later revelation. 'Amr Ibn al-Aas reported that the Messenger of Allah (aka Muhammad (pbuh)) said: "The distinguishing feature between our fast and the fast of the People of the Book is in the eating at the time just before dawn." [reported in Sahih Muslim]
The Sahoor is blessed. The Prophet Muhammad (pbuh) usually had a sahoor when he fasted; to follow that example is to follow the Sunnah for Muslims. Eating a sahoor makes the fasting easier for the person who is fasting, and the fact that it is not only permissible but in fact encouraged is considered one of God's blessings to His servants. It also increases the desire in the person to want to continue to fast because of the ease upon the fasting person, and makes Muslims stand out from the People of the Book. For these reasons, Muhammad (pbuh) called it "the blessed meal." The greatest blessing may be that God Forgives and shows Mercy to the one who does it, and His angels will pray on the person's behalf.
Abu Hurairah (R) said that the Messenger of Allah (saw) said: "Verily Allah placed Barakah (blessing) in the sahoor and in perfect measurement (weighing)." [Ash-Shairazee]
'Abdullah Ibn Haarith said that one of the Sahabah (companion) said: 'I entered the house of the Messenger (S) whilst he was taking the Sahoor, and he said: "Indeed it (the Sahoor) is blessing that Allah has given to you so do not leave it out." [An-Nasaaee and Ahmad]
Abu Sa'eed al-Khudree said that the Messenger (saw) said: "Eating the Sahoor is blessed. Do not neglect it even if you take a gulp of water, because Allah and His angels invoke blessings upon those who partake in the pre-dawn meal." [Ahmad]
Muhammad (pbuh) said: "The best sahoor for the believer is
dates." [Abu Dawood, Al-Baihaqee and Ibn Hibbaan] Scholars have added a note: If one does not find food to eat then a gulp of water would suffice as is substantiated in the
hadith.
Dates always become a very popular
fruit during
Ramadan and people eat them for both Sahoor and
iftar.
It is recommended to delay the sahoor until just before dawn. Zaid ibn Thaabit said: "We ate the Sahoor with the Messenger (saw), then we got up to offer the Salat (prayer - in this case the Fajr prayer). I asked "What was the time between the Adhan (call to prayer) and the Sahoor?" He said: "(The time it would take) to recite fifty verses." [Bukhari and Muslim]
After the beginning of dawn, eating, drinking, and marital relations with one's spouse must stop and the fast begins. Scholars of different schools of thought have laid out specific guidelines as to when one should stop eating, you are allowed to eat if you are uncertain that dawn has started.. Some scholars are divided on the issue as to what you should do if you have food in your mouth when dawn breaks; one school of thought says that if you should spit whatever you have out, another says you can swallow what you have but no more. Adherence to either is a matter of personal opinion. Most people stop eating a few minutes early and avoid the choice.
A Muslim can fast without having a sahoor, but it isn't recommended and one would miss out on extra blessings. There is a hadith where the Prophet Muhammad (pbuh) came home one day and found out that there was no food in the house. He then declared "I am fasting, then," and fasted the rest of the time until sunset. It is very important that the Muslim does not allow this great blessing from his Merciful Lord to escape him, so while it is not required, it is at least strongly encouraged.
Some fatwas regarding the sahoor are availible at:
http://www.islam-online.net/fatwa/english/FatwaDisplay.asp?hFatwaID=4166
http://www.islam-online.net/fatwa/english/FatwaDisplay.asp?hFatwaID=85800
http://www.islam-online.net/fatwa/english/FatwaDisplay.asp?hFatwaID=107249
Sources:
http://www.themodernreligion.com/ramadan/sahoor-rulings.html