Narrated ‘Abdullah (radiallaahu `anhu):
The Prophet (sallallaahu `alayhi wasallam) fasted for days continuously; the people also did the same but it was difficult for them. So, the Prophet (sallallaahu `alayhi wasallam) forbade them (to fast continuously for more than one day). They slid, “But you fast without break (no food was taken in the evening or in the morning).” The Prophet (sallallaahu `alayhi wasallam) replied, “I am not like you, for I am provided with food and drink (by Allah).”
The Prophet (peace and blessings of Allaah be upon him) used to fast continually, and Allaah gave him the strength to do that, but he forbade his ummah to do that out of compassion and mercy towards them.
Shaykh Ibn ‘Uthaymeen said in al-Sharh al-Mumti’, 6/443:
It appears that the ruling with regard to continual fasting is that it is haraam.
And Allaah knows best.
Narrated Anas bin Malik (radiallaahu `anhu):
The Prophet (sallallaahu `alayhi wasallam) said, “Take Suhur as there is a blessing in it.”
Having the pre-dawn meal or suhoor is highly recommended. There’s blessing in FOOD. How can you not appreciate that? :P
Having said that, you must know that having suhoor is not a ‘condition’ for the fast to be valid. If you missed it due to sleep or some other reason, you may continue your fast without hesitation.
When should you take your suhoor meal? Till dawn or the adhaan?
Volume 3, Book 31, Number 142:
Narrated ‘Aisha (radiallaahu `anhaa):
Bilal (radiallaahu `anhu) used to pronounce the Adhan at night, so Allah’s Apostle (sallallaahu `alayhi wasallam)? said, “Carry on taking your meals (eat and drink) till Ibn Um Maktum [Bilal] pronounces the Adhan, for he does not pronounce it till it is dawn.
Volume 3, Book 31, Number 143:
Narrated Sahl bin Sad (radiallaahu `anhu):
I used to take my Suhur meals with my family and then hurry up for presenting myself for the (Fajr) prayer with Allah’s Apostle (sallallaahu `alayhi wasallam).
Volume 3, Book 31, Number 144:
Narrated Anas (radiallaahu `anhu):
Zaid bin Thabit (radiallaahu `anhu) said, “We took the Suhur with the Prophet (sallallaahu `alayhi wasallam). Then he stood for the prayer.” I asked, “What was the interval between the Suhur and the Adhan?” He replied, “The interval was sufficient to recite fifty verses of the Quran.”
The ruling is that you “eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night).” [al-Baqarah 2:187]
Translation: eat and drink till dawn starts. Whether the adhaan starts before it or after is irrelevant; you just have to look for the dawn.
Also, it’s better to delay the suhoor meal till dawn. Imam Ahmad recorded Abu Dharr saying that Allah’s Messenger said:
«لَا تَزَالُ أُمَّتِي بِخَيْرٍ مَا عَجَّلُوا الْإِفْطَارَ وَأَخَّرُوا السُّحُور»
My Ummah will always retain goodness as long as they hasten in breaking the fast and delay the Suhur.