Assalam-u-Alaikum Wa Rahmatullahi Wa Barakatuhu,
"And verily We have displayed for mankind in this Qur'an all kind of similitudes, but most of mankind refuse aught save disbelief."
Duration of Fast (Saum)
[2.Surah Al-Baqarah: Ayah 187]
"And eat and drink until the whiteness of the day becomes distinct from the blackness of the night at dawn, then complete the fast till night."
Doing Sehri Late
[Sahih Bukhari : Volume 3, Book 31, Number 140,146]
Narrated Hazrat Adi bin Hatim (Radi Allah Anhu): When the above verses was revealed: "Until the white thread appears to you , distinct from the black thread," I took two (hair) strings one black and one white , and kept them under my pillow and went on looking at them throughout the night but could not make anything out of it. So, the next morning I went to Allah's Messenger Muhammad (sal-allahu-alleihi-wasallam), and told him the whole story. He explained me, "That the verse means the darkness of night and blackness of drawn."
Narrated Anas bin Malik (Radi Allah Anhu), The Prophet Muhammad (sal-allahu-alleihi-wasallam) said, "Take Sehri as there is a blessing in it."
Interval between Sehri and Fajr Prayer
[Sahih Bukhari : Volume 3, Book 31, Number 144]
Narrated Hazrat Anas (Radi Allah Anhu) : Zaid bin Thabit (Radi Allah Anhu) said, " We took the Sehri with Prophet Muhammad (sal-allahu-alleihi-wasallam) then He (sal-allahu-alleihi-wasallam) stood for As-Salat (the prayer)." I asked, "What was the interval between the Sahur and the Adhan?" He replied, "The interval was sufficient to recite fifty verses of Quran." (Sahih Bukhari)
Doing Iftar Early
[Sahih Bukhari : Volume 3, Book 31, Number 178,177,180]
Narrated Hazrat Sahl bin Sa'd (Radi Allah Anhu): Allah's Messenger Muhammad (sal-allahu-alleihi-wasallam) said, "The people will remain on the right path as long as they hasten the Iftar."
Narrated Ibn Abi Aufa (Radi Allah Anhu), Prophet Muhammad (sal-allahu-alleihi-wasallam) said, "When you see night falling from this side, the person observing fast should break its fast", and he beckoned with his finger towards east.
Hazrat Asma bin Abi Bakr (Radi Allah Anhu) said, "We broke our fast during the lifetime of the Prophet Muhammad (sal-allahu-alleihi-wasallam) on a cloudy day and then the sun appeared."