What is the Sharia basis of the Udhiyah?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
The Sharia basis of the Udhiyah (sacrificial offering) is firmly established through the Quran, the Sunnah, and the Consensus (Ijma') of the Muslims:
1. Evidence from the Holy Quran
Allah the Exalted says {what means}: "And the camels and cattle We have appointed for you as among the symbols of Allah; for you therein is good." [Al-Hajj/36]. He also says {what means}: "So pray to your Lord and sacrifice [to Him alone]" [Al-Kawthar/2]. According to the most well-known scholarly interpretations of this verse, "prayer" refers to the Eid prayer, and "sacrifice" refers to the slaughtering of the Udhiyah.
2. Evidence from the Sunnah
Al-Bara' bin 'Azib (may Allah be pleased with him) narrated that the Prophet ﷺ said: "The first thing we start with on this day of ours is to pray, then we return and sacrifice. Whoever does that has followed our Sunnah, and whoever slaughters before [the prayer], it is merely meat he has provided for his family; it is not part of the ritual sacrifice in any way" [Reported by Bukhari & Muslim].
Anas (may Allah be pleased with him) narrated: "The Prophet ﷺ sacrificed two white rams with horns. He slaughtered them with his own hand, mentioned the name of Allah (Tasmiyah), and said the Takbir" [Reported by Bukhari & Muslim].
3. Evidence from Scholarly Consensus (Ijma')
The Muslims have reached a unanimous consensus on the Sharia basis of the Udhiyah, and no one among the scholars has disagreed with this. [Al-Sherbini, Mughni al-Muhtaj, Vol.6/P.122].And Allah the Exalted knows best.
Can I start fasting based on the moon sighting of another country?
You must follow the moon sighting of the country you are in.
What advice do you have for those who spend their nights and days of Ramadan watching TV?
Time is too precious to be wasted on entertainment, let alone in the blessed month of Ramadan, where a Muslim should strive for reward and forgiveness.
What is the ruling on someone who eats or drinks thinking that the night is still present, then realizes that dawn has broken?
Whoever eats or drinks thinking that the night is still present, then later discovers that dawn has broken, must refrain from eating and drinking for the rest of the day out of respect for the sacred month. However, they must make up that day after Ramadan, and there is no sin upon them.