Prophet Abraham(as) was born on this day and in accordance with reports cited by Shaikh Mufid and Shaikh Tusi, Imam Ali (peace be upon him) married Sayyeda Fatima Zahra (peace be upon her) on this day.
Like two star clusters coming together to form a supermassive galaxy, the marriage of Ali(as) and Fatima(sa) produced the purest and most noble dynasty to ever exist, prophesied by Abraham a thousand years before (Book of Genesis 17:20)
This is a very blessed day, and there are several observances relating to it as follows:
1.It is recommended to observe fasting on this day, for its reward is equal to the reward of eighty-month worship.mentioned in the book 'Man La Yahzaruh Al-Faqih'
2.It is recommended to offer Salat Fatimah on the "Night". According to Shaykh al-Tusi, this prayer consists of four units (2x2). In each unit, Surah al-Fatihah is recited once and Surah al-Tawhid repeated fifty times. After completion of the prayer, recite the Tasbih of Sayyeda Fatima (peace be upon her) and say:
سُبْحَانَ ذِي ٱلْعِزِّ ٱلشَّامِخِ ٱلْمُنِيفِ
subhana dhi al`izzi alshshamikhi almunifi
Glory be to the Lord of Honor and Sublime Authority.
سُبْحَانَ ذِي ٱلْجَلاَلِ ٱلْبَاذِخِ ٱلْعَظِيمِ
subhana dhi aljalali albadhikhi al`azimi
Glory be to the Lord of Majesty and Exalted Greatness.
سُبْحَانَ ذِي ٱلْمُلْكِ ٱلْفَاخِرِ ٱلْقَدِيمِ
subhana dhi almulki alfakhiri alqadimi
Glory be to the Lord of eternal, splendid sovereignty.
Glory be to Him Who knows the exact time and place of the bird dipping down through the air.
سُبحَانَ مَنْ هُوَ هٰكَذَا لاَ هكَذَا غَيْرُهُ
subhana man huwa hakadha la hakadha ghayruhu
Glory be to Him Who is like this and no one other than Him is like this.
3.It is recommended to offer a two unit prayer half an hour before midday (noon). In each unit, Surah al-Fatihah is recited once and Surah al-Tawhid, Ayah al-Kursi, and Surah al-Qadr repeated ten times each.
4.One who fears an oppressor and says the following words on this day will be saved, by Almighty Allah:
“O‟ my God! This is the crescent moon of the month which You have exalted. You honored it, declared it, raised it, praised its first ten days, and established ceremonies during it with prosperity for the worshippers.
You also made this month especial with the Invocation Day on which You clearly showed the true faith to the atheists and bestowed a noble rank on those who prepared for it. You also placed other goods and secrets in it that shall be explained with clear narrations and sound reasons
.You also established it as a month in preparation for the next month being the month of trial. You started with Kindness and Favors after we encounter the contentment with manifold calamities that occurred in fighting the enemies.
Please unite our hearts in what is good with Your Mercy! O‟ the Most Compassionate, Most Merciful.”
Section 6 On the Nobility of the First Day of Dhul-hijjah
It has been written in many narrations on the authority of the Divine Leaders (as) that the first day of Zil-Hijjah is the birthday of Abraham - the Friend of God (as). Abu Ja‟far al-Tusi - may God have mercy upon him - has also chosen this viewpoint in the book Misbah even though Abraham‟s (as) birthday has been reported to be on a different date based on another narration.
The following has been reported by Abu Ja‟far Muhammad ibn Babuyih in his book Man La Yahzaruh Al-Faqih and my grandfather Abu Ja‟far al-Tusi through several documents on the authority of our Master Musa ibn Ja‟far (as) said, “God will record the reward of eighty months of fasting for anyone who fasts on the first day of Zil-Hijjah."
My grandfather Abu Ja‟far al-Tusi has added the following, "This is the day on which Abrahim the Friend of the Most Merciful was born and God chose him (as) as his Intimate Friend."
Abu Ja‟far al-Tusi - may God have Mercy upon him - added, "On the first day of Zil-Hijjah God revealed the Chapter Repentance to the Prophet (as) and the Prophet (as) sent it to Mecca by means of Abu Bakr. Then it was revealed to the Prophet (as) that no one except the Prophet (as) or a man belonging to his household is allowed to deliver the Chapter Repentance. Thus, the Prophet (as) dispatched Ali (as) to Mecca and he (as) reached Abu Bakr on the third day of Zil-Hijjah in the Al-Rawha station (near Mecca) and he (as) took the Chapter Repentance from Abu Bakr. Finally Ali (as) preached it to the people on the Arafa day or the offering day (the ninth or the tenth day of Dhul-hijjah) on behalf of God‟s Prophet (as) during the Hajj pilgrimage.