It is also narrated from Ibn Abbaas(radhiyallanhu) that Rasulullah(sallallahu alaiyhi wassallam) said: " No days are as weighty with Allah and so liked by Him for good deeds than the first ten days of Zul-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(sallallahu alaiyhi wassallam) 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".(Tirmizi)
The 9th day of Zulhijjah:
The 9th day of Zulhijjah is called 'Youmul - Arafah" (The Day of Arafah). This is the date when the Hujjaj ( pilgrims) assemble on the plain of Arafat, six miles away from Makkah al-Mukarramah, where they perform the most essential part of the prescribed duties of hajj, namely, the Wuqoof of Arafat (the stay in Arafat).
The Fast of Youmul 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 'Youmul Arafah' has been emphasized by the Prophet(sallallahu alaiyhi wassallam) 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(radhiyallahu anhu) reported that Rasullullah(sallallahu alaiyhi wassallam) said: " I have hope in Allah Ta'ala that the fast of Arafaat will be an atonement for the sins of the past and the forthcoming year." (Tirmizi)
Beginning from the Fajr of the 9th Zulhijjah 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. However, male Muslims should recite it in a loud voice, while females should recite it in a low voice.