Why we should fast the first 9 days of Dhul Hijjah?

Today we will talk about the important of those days and we will show you evidence in the holly Quran and in the hadith Sharif , we all wondering why we should fast those first 9 days of Dhul Hijjah , why they are so important like that , and also we will know the reward from Allah if we fast the first 9 days of Dhul Hijjah.

Why those days are so special?

Allah says in the Qur'an: "By the dawn and by the ten nights …” [Al-Qur'an 89:1-2]

Ibn Kathir said that "the ten nights" referred to here are the ten days of Dhul-Hijjah, and this opinion was also held by Ibn Abbas, Ibn az-Zubair, Mujahid and others.

The Prophet sallallahu alayhi wasallam too, has clearly mentioned the importance and the virtue of these blessed moments. It is reported by Abdullah Ibne Abbaas radhiyallahu anhuma that the Prophet sallallahu alayhi wasallam said, “No good deeds done on other days are superior to those done on these (first ten days of Dhul Hijjah).” Thereupon, some companions of the Prophet sallallahu alayhi wasallam said, “Not even Jihaad ? ” He replied, “Not even jihaad, except that of a man who does it by putting himself and his property in danger (for Allah’s sake) and does not return with any of these things.”Bukhaari V1 pp132 .

Moreover ,what other virtue can be greater for these blessed days than the fact that certain specific devotions cannot be performed but in these specified days. Allah Almighty has specifically chosen these days for the fulfillment of two of the most important devotions, viz. Hajj and Qurbaani.
also read Benefits of the first 10 days of dhul-hijjah .

What we should to have the blessing for Allah in those days ( first 10 days of Dhul Hijjah )?
Prayer - It is highly recommended to perform the obligatory acts at their prescribed times (as early as possible) and to increase oneself in the superogatory acts, for indeed, this is what brings a person closer to their Lord. The Messenger of Allah, peace be upon him , said: "Upon you is to increase in your prostration to Allah, for verily you do not prostrate to Allah with even one prostration, except that He raises you in degrees and decreases your sins because of it." [Reported by Muslim]

Fasting - This has been mentioned as one of the acts of righteousness where Hanbada ibn Khalid reports on the authority of his wife who reports that some of the wives of the Prophet, peace be upon him, said, "The Prophet, upon whom be peace, would fast on the ninth of Dhul-Hijjah, the day of Ashura and three days in every month." [Recorded by Ahmad, Abu Dawud, an-Nisa'i and others] Imam an-Nawawi said that fasting in these ten days is extremely recommended.
Saying allahu akbar, la illaha illallah and alhamdulillah - It is found in the aforementioned narration of Ibn 'Umar: "So increase yourselves in saying la illaha illallah, allahu akbar and alhamdulillah."

Imam al-Bukhari, may Allah have mercy on him, said: "Ibn 'Umar and Abu Hurayrah, may Allah be pleased with them both, used to go out to the markets in the ten days saying the takbir causing the people to follow them in this action."

He also said: Umar ibn al-Khattab used to say the takbir in his mimbar in Mina, whereupon the people of the mosque hearing 'Umar, would start to say the takbir as would the people in the markets until the whole of Mina was locked in glorifying Allah."

Ibn 'Umar used to say the takbir in Mina during these ten days and after prayers, whilst on his bed, in his tent, in his gathering and whilst walking. What is recommended is to say the takbir aloud due to the fact that 'Umar ibn al-Khattab, his son and Abu Hurayrah used to do likewise, may Allah be pleased with them all.

Strive with us O Muslims in reviving this sunnah that has become lost in these times and it was almost forgotten, even amongst the people of righteousness and goodness all of which is unfortunately in opposition to what the best of generations were upon (preserving and maintaining the superogatory acts).

There are a number of ways of making takbir that have been narrated by the companions and their followers and from these ways is the following: 

Allahu akbar, allahu akbar, allahu akbar kabirun.
Allahu akbar, allahu akbar, la ilaha illallah, wallahu akbar, wallahu akbar, wa lillahil hamd.
Allahu akbar, allahu akbar, allahu akbar, la ilaha illallah, wallahu akbar, allahu akbar wa lillahil hamd.

What is the reward that we will get If we fast those days ?

Fasting on the day of 'Arafah - Fasting has been affirmed on the day of 'Arafah, where it has been confirmed from the Prophet, peace be upon him, that he said regarding fasting on the day of 'Arafah:

"Be content with the fact that Allah will expiate for you your sins for the year before (the day of 'Arafah) and the year after (the day of 'Arafah)." [Reported by Muslim]