Sighting of the Crescent by one Person
     The scholars of fiqh agree that if only one person sees    the new moon, he is to fast. 'Ata differs and says that    he is not to fast until someone else also sights the new    moon with him. The correct position is that he is to    break the fast, as ash-Shaf'i and Abu Thaur have ruled.
    The Prophet has based the fast and its breaking on the    sighting of the moon. One's own sight is enough for him    and there is no need for another person's sighting.
    
Essential Elements of the Fast
The fast has two essential elements (literally, "pillars") that must be fulfilled for it to be valid and acceptable. They are:
Abstaining from those acts that break the fast
     This point is based on the Qur'anic verse: "Eat and drink    until the white thread becomes distinct to you from the    black thread of the dawn. Then strictly observe the fast    until nightfall."
         This is also based on the following hadith: "When the    verse 'Eat and drink until the white thread becomes    distinct to you...' was revealed, I took a black thread    and a white thread and placed them underneath my pillow.
    During the night I looked at them to see if I could    distinguish between them. In the morning I went to the    Messenger of Allah and mentioned that to him and he said:    'It is the black of the night and the white of the day.'"    
Intention
     Allah instructs in the Qur'an: "And they are ordained    nothing else than to serve Allah, keeping religion pure    for Him." The Prophet, upon whom be peace, said: "Actions    are judged according to the intention behind them, and    for everyone is what he intended."
         The intention must be made before fajr and during every    night of Ramadan. This point is based on the hadith of    Hafsah which reported that the Prophet said: "Whoever    does not determine to fast before fajr will have no fast"    (that is, it won't be accepted). This is related by    Ahmad, an-Nasa'i, at-Tirmidhi, Abu Dawud, and Ibn Majah.
    Ibn Khuzaimah and Ibn Hibban have classified it as sahih.
         The intention is valid during any part of the night. It    need not be spoken, as it is in reality an act of the    heart which does not involve the tongue. It will be    fulfilled by one's intention to fast out of obedience to    Allah and for seeking His pleasure.
         If one eats one's pre-dawn meal (sahoor) with the    intention of fasting and to get closer to Allah by such    abstinence, then one has performed the intention. If one    determines that one will fast on the next day solely for    the sake of Allah, then one has performed the intention    even if a pre-dawn meal was not consumed.
         According to many of the jurists, the intention for a    voluntary fast may be made at any time before any food is    consumed. This opinion is based on 'Aishah's hadith: "The    Prophet came to us one day and said: 'Do you have any    [food]?' We said, 'No.' He said: 'Therefore, I am    fasting." This is related by Muslim and Abu Dawud.
         The Hanafiyyah and Shaf'iyyah stipulate that the    intention must be made before noon (for voluntary fasts).
    The apparent opinion of Ibn Mas'ud and Ahmad is that the    intention may be made before or after noon.
    
We are identifying and building the related set of Ayahs for this Hadith. Please share your feedback and let us know if you identify any referencing issues.
"When a person dies, his works end, except for three: ongoing charity, knowledge that is benefited from, and a righteous child who prays for him."
Prophet Mohammed (PBUH)
"The best of what a man leaves behind are three: a righteous child who supplicates for him, ongoing charity the reward of which reaches him, and knowledge that is acted upon after him."
Sunan Ibn Mājah
"Every day two angels come down from Heaven and one of them says, 'O Allah! Compensate every person who spends in Your Cause,' and the other (angel) says, 'O Allah! Destroy every miser.'"
Sahih Bukhari