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.
What is the ruling on fasting the six days of Shawwal?
Fasting the six days of Shawwal is Sunnah. The Prophet ﷺ said: "Whoever fasts Ramadan and then follows it with six days of Shawwal, it is as if they have fasted for a lifetime." [Narrated by Muslim]
This is because fasting one month of Ramadan is rewarded as fasting for ten months, and the six days are equivalent to sixty days, completing a full year of fasting.
What is the ruling on objecting to the Mosque Imam regarding the joining of prayers due to rain?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is not permissible for any of the congregants to object to the Imam in the mosque, whether the objection is to demand the joining of prayers or to oppose it; for the general principle is that the Imam possesses the religious knowledge (Al-Ilm al-Shar‘i) that qualifies him to make the decision in this matter. And Allah the Exalted knows best."
Is Zakah (obligatory charity) due on the Zakah money received by a poor person, and reached a Nissab (minimum amount liable for Zakah), and a whole lunar year had lapsed over having it in his possession?
Yes, the poor who possessed a Nissab for a whole lunar year is obliged to pay the Zakah due on that money even if it was given to him as a Zakah money in the first place. And Allah Knows Best.