The month of dhul-Hijjah is indeed a month of tremendous virtues and blessings. The First Ten Days of this month are especially significant and are among the most magnificent days in the Islamic calendar.
It is reported from Ibn Abbaas (ra) that the Prophet (pbuh) said:
"There is no day wherein any good action is more beloved to Allah than these ten days (the first ten days of Dhul-Hijjah)".The Sahaabah (ra) enquired: " Not even Jihaad in the path of Allah? "(i.e. are actions performed in these days more beloved than even the act of Jihaad)". "Not even Jihaad in the path of Allah," replied the prophet (pbuh)" with the exception of that person who left with his life and wealth (in the path of Allah) and did not return with any of it (i.e. he is martyred)".
(Bukhari, Tabraani)
It is also narrated from Ibn Abbaas (ra) that the Prophet (pbuh) said:
"No days are as weighty with Allah and so liked by Him for good deeds than the first ten days of Dhul-Hijjah. Therefore in these days increasingly recite: La ilaha illAllah, Allahu Akbar, Al-Hamdu-lillah, Sub-hanallah."
(Tabraani)
Fasts in the First 10 Days:
The Prophet (pnuh) has said,
"One fast during these days is equal to the fasting of one complete year, and the worship of one night during this period is equal to the worship in the "Lailatul-Qadr".
(Tirmidhi)
The 9th day of Dul-Hijjah:
The 9th day of Dul-Hijjah is called 'Youmul - Arafah" (The Day of Arafah). This is the date when the Hujjaj (pilgrims) assemble on the plain of Arafah, six miles away from Makkah al-Mukarramah, where they perform the most essential part of the prescribed duties of hajj, namely, the Wuqoof of Arafah (the stay in Arafah).
The Fast of Youm-ul Arafah:
For those not performing hajj, it is mustahabb (desirable) to fast on this day according to their own lunar calendar dates of their own country . The fast of 'Youm-ul Arafah' has been emphasized by the Prophet (pbuh) as a mustahab (desirable) act. According to a hadith, the fast of this day becomes a cause, hopefully so, of forgiveness for sins committed in one year.
Abu Qataadah (ra) reported that the Prophet (pbuh) said:
"I have hope in Allah that the fast of Arafah will be an atonement for the sins of the past and the forthcoming year."
(Tirmidhi)
Takbir-ut-tashriq:
Beginning from the Fajr of the 9th Dhul-Hijjah up to the Asr prayer of the 13th, it is obligatory on each Muslim to recite the Takbir of Tashriq after every fard prayer in the following words.
"Allahu Akbar, Allahu Akbar,La Ilaha Illallahu, Wallahu Akbar, Allahu Akbar wa lillahilhamd."
(There is no god but Allah and Allah is the greatest, Allah is the greatest and to Allah belongs all praise.)
According to authentic Islamic sources, it is obligatory on each Muslim, to recite this Takbir after every fard salah. For women also, it is commendable though not obligatory. Whether one is performing salah with Jama'ah (collectively) or on one's own (individually) makes no difference. One must recite the Takbir.