In this article, you can read some narrations about the day of Ghadir.

Chapter One: The place of Eid Ghadir in the religion

1- Eid of Caliphate and Wilayah

I went to Imam Sadiq (AS) and said: Do Muslims have Eid other than Eid al-Adha, Eid al-Fitr, and Friday? 
Imam (AS) said: Yes, the day when the Messenger of God (PBUH&HP) appointed the Commanders of the Faithful (to the caliphate and guardianship.

2- The best Eid of the nation

The Messenger of Allah (PBUH&HP) said:
Ghadir Day is the highest Eid of my nation and it is the day that Allah Almighty commanded. On that day, I will appoint my brother Ali ibn Abi Talib as the flag bearer (and commander) of my ummah, so that the people after him will be guided by him, and that is the day when Allah completed the religion and completed the blessings on my ummah, and He liked Islam as a religion for them.

3- The great feast of Allah

Imam Sadiq (AS) said:

The day of Ghadir is the great feast of Allah, God did not send a prophet, unless he took this day as Eid and recognized its greatness, and the name of this day in heaven is the day of the covenant and on earth, the day of the firm covenant and public presence.

4- Eid ul-Fitr

Imam Sadiq (AS) was asked: do believers have any other Eid besides Eid al-Fitr and Eid al-Adha and Friday? And he answered:
Yes, they have a bigger Eid and that is the day when the Commander of the Faithful (AS) was raised in Ghadir, and the Messenger of God placed the issue of guardianship on the shoulders of men and women.

5- Day of renewal of allegiance

Ammar bin Hariz says:

On the eighteenth day of the month of DhulHija, I arrived at the service of Imam Sadiq (AS) and found him fasting. The Imam said to me: Today is a great day, Allah has given it greatness and on that day he completed the religion of the believers and completed the blessings on them and renewed the previous covenant.

6- Heavenly Eid

Imam Reza (AS) said:

My father quoted his father (Imam Sadiq (AS)) as saying:
Ghadir Day is more famous in the sky than on earth.

7- Unique Eid

Ali (AS) said:

Today (Eid Ghadir) is a very great day.

On this day, the opening has come and the status (of those who deserved it) has risen, and the proofs of Allah have been clarified, and the position of purity has been clearly spoken, and today is the day of the completion of religion and the day of the covenant.

8- Happy Eid

Imam Sadiq (AS) said:

I swear by God, if the people knew the true virtue of "Ghadir Day", the angels would shake hands with them ten times a day, and the gifts of God to the one who knew that day cannot be counted.

9- Clarification Eid

Imam Sadiq (AS) said:

... The day of Ghadir among the days of Eid al-Fitr and Eid al-Adha and Friday is like the moon among the stars.

10- One of the four divine holidays

Imam Sadiq (AS) said:

When the Day of Judgment comes, the four days will hasten to Allah as the bride will hasten to her chamber. Those days are: Eid al-Fitr and Eid al-Adha and Friday and Ghadir.

Chapter 2: The merits and demerits of Ghadir

11- Day of message and providence

The Prophet (PBUH&HP) (on the day of Ghadir) said:

O Muslims! Let those present inform the absentees: I recommend the one who believes in me and acknowledges me to the guardianship of Ali, beware that the guardianship of Ali is my guardianship and my guardianship is the guardianship of my God. This was a covenant from my Lord which He commanded me to deliver to you.

12- Feeding day

Imam Sadiq (AS) said:

Eid Ghadir is the day when the Prophet (PBUH&HP) raised Ali (AS) as the flag bearer for the people and revealed his virtue on this day and introduced his successor, then he fasted that day in gratitude to the Almighty Allah and that day is the day of fasting, worship, feeding, and visiting religious brothers. That day is the day of gaining the pleasure of the merciful Allah and rubbing the dust of the devil's nose.

13- Gift day

Ali (AS) (in the sermon of Eid Ghadir) said:

When you reach each other, shake hands with each other and give gifts to each other on this day; whoever was there and heard these words, let him go to the poor, let the rich go to the poor, and let the strong go to the weak, prophet (PBUH&HP) commanded me so.

14- Day of sponsorship

The Commander of the Faithful (AS) said:

... How will it be for someone who is responsible for the living expenses of a number of believing men and women (on the Day of Ghadir), if I guarantee him/her to Allah that he will be safe from disbelief and poverty.

15- Thanksgiving and happiness day

Imam Sadiq (AS) said:

Eid Ghadir is a day of worship, prayer, thanksgiving, and praise to Allah, and it is a day of joy and happiness for the sake of our family, may God bless them, and I would like you to fast that day.

16- Charity Day

It was narrated from Imam Sadiq (AS) that he said:

One dirham to brothers with faith and knowledge on the day of Eid Ghadir is equal to one thousand dirhams, so give alms to your brothers on this day and make every believing man and woman happy.

17- Day of joy and happiness

Imam Sadiq (AS) said:
Ghadir is the day of Eid and joy and happiness and the day of fasting is as a thanksgiving for divine blessings.

18- Congratulations

Ali (AS) said:

Return home after the gathering (on the day of Ghadir), may Allah have mercy on you. Develop for your family, do good to your brothers, thank Allah for the blessing He has given you, unite so Allah will unite you, do good so Allah will establish your friendship, give each other Allah's blessing and congratulations, as Allah has congratulated you on this day by rewarding you many times over other Eids, such rewards will not be except on the day of Eid Ghadir.

19- Day of greetings and innocence

I said to Imam Sadiq (AS): Do Muslims have any other Eid besides those two? 
He said: Yes, the greatest and best Eid. 
I said: What day is it?
He said: The day when Amir al-Mu'minin was appointed as the flag bearer of the people.
I said: on that day, what should we do? 
He said: Fast and send greetings to Muhammad and his family and seek acquittal from the oppressors because the prophets instructed the successors to observe Eid on the day when the successor is chosen.

20- Eid al-Adha

Imam Sadiq (AS) said:

On the day of Eid-ul-Ghadir, remember Allah with fasting and worship and remembrance of the Prophet and his family, because the Messenger of Allah instructed the Commanders of the Faithful to observe Eid on that day, just as the prophets instructed their successors to observe that day as Eid. They did the same.

Resources

1.  The Holy Quran.
2. Amali Sheikh Sadough, Islamic Library.
3. QurbalAsnad Abdullah Ja'far al-Humairi, Al-Bayt.
4. Mesbah Al-Muttahid, Sheikh Tusi, Shiite Fiqh Foundation.
5. Wasael Shiah, Sheikh Har Ameli, Islamic Library.
6. Safinat al-Bahar, Sheikh Abbas Qomi, Aswa.
    

Lady Zainab (SA) is an icon of purity, bravery, and steadfastness.Though she lived 14 centuries ago, her personality and teachings continue to guide men and women till now/to this day. She is the fruit of the tree of Prophethood nourished by Imamat. Lady Zainab (SA), the daughter of Imam Ali (As), has several attributes and titles associated with her, such as Al-Aqilah the noblewoman, Al-Aalimah or the knowledgeable woman and Aminatu-al-Allah, the faithful of Allah (SWT).
She belonged to a holy lineage; her mother was Lady Fatimah al-Zahra (SA), - the daughter of Prophet Muhammad (PBUH & HP) - and was actually a reflection of her father in the worship of Allah, piety, self-discipline, virtues, clemency, veneration, and the other features of perfection thus her father named her the chief of the women of the worlds and such a great mother nurtured Lady Zainab. 

Lady Zainab’s life

Lady Zainab’s father, Imam Ali (AS) honoured as the representative, successor and heir to Prophet Muhammad (PBUH&HP) was given remarkable titles like ‘the chief of the prophets’ successors’, ‘leader of the pious ones’ and ‘the head of the worshippers’ by Prophet Muhammad (PBUH&HP) himself.  With innumerable merits and unrivalled sacrifices for Islam he was recognised and reputed as the most knowledgeable, the most magnanimous, the most generous, the most abstinent, the most trustworthy, the best worshipper, the most faithful, and above all, the most pious and the bravest of all Muslims. In other words, he was the best Muslim after the Holy Prophet Muhammad. (PBUH&HP).

Lady Zainab  (SA), hence, was  born into the most pious family and raised  under the care of the best human beings therefore she learnt many things that composed her perfect personality from the etiquettes of her parents and her brothers.  Since early life, she was marvellous in her intellect and wisdom and had learnt the Holy Quran by heart as well as the Prophet’s sayings regarding Islamic laws, rules of education and principles of ethics.

Throughout her life she faced one tribulation after another, but emerged strong and victorious in all her trials. She then witnessed the martyrdom of her mother, father and brothers - Imam Hasan and Imam Hussain (AS) - and in Karbala where all male members of her family were brutally martyred including her own sons Awn and Muhammad, and all the women folk were taken into captivity. But despite all these vicissitudes she always remained a source of strength and a caretaker for the survivors of the tragedy of Karbala and the flagbearer of the message of this great event. She is the epitome of selflessness and perseverance, the embodiment of patience and courage in the face of oppressors and the personification of knowledge and purity. Despite all the hardships she endured in Karbala she decided to preserve and propagate the true message of Karbala While her bravery, eloquence, courage, asceticism, chastity and caring nature towards the survivors of the tragedy of Karbala has been and still is unparalleled in history. 

The Holy Prophet Muhammad (PBUH&HP) says, “Whoever tries to fulfil the needs of a sick person, whether they fulfil it or not, they will be cleansed of their sins like the day they were born.”[1] In another tradition,   he has said, “Whoever looks after the sick for an entire day, Allah (SWT) will raise them up with Prophet Abraham.”[2] If we would take only these two traditions into consideration, we can understand the greatness of Lady Zainab (SA) who cared for Imam Sajjad (AS) and all the children and women who had got sick or were injured after what happened in Karbala. Therefore, taking inspiration from her, the 5th of Jamadi-Al-Awwal which is her birthday is celebrated as the Nurses’ Day in the Islamic calendar. 

References:

1.  Kitab Man La Yahzarul Faqih, V.4, Pg.16 
2.   Sawab ul Aamal, Pg. 341
3.    https://www.al-islam.org/lady-zaynab-badr-shahin/life-lady-zaynab 
4.  https://www.al-islam.org/victory-truth-life-zaynab-bint-ali-muna-haeri-bilgrami