Dhul Hijah is a month of worship that brings many benefits

In the name of Allah, the Merciful, the Compassionate.

►Allah says: “By the Dawn; By the ten nights” [Surah Al-Fajr:1-2]. This oath substantiates the greatness and sacredness of these ten nights in the eyes of Allah. Dhul Hijah is a month of worship that brings many benefits.

⇨Regarding these blessed days; the Prophet (peace be upon him) said: “There are no days in which righteous deeds are more beloved to Allah than these ten days.” The people asked , “Not even Jihad for the sake of Allah?” He said, “Not even Jihad for the sake of Allah, except in the case of a man who went out, giving himself and his wealth up for the cause (of Allah), and came back with nothing.” [Sahih Al-Bukhari]

►Allah says: " … and remember the name of Allah in the appointed days." [Al-Qur'an 2:203]
It is Sunnah to recite takbeer (Allahu Akbar), tahmeed (Alhamdulillah), tahleel (Laa ilaaha ill-Allah), and tasbeeh (SubhanAllah) on these appointed days that is during the first ten days of Dhul Hijjah and also it was in the aforementioned narration of Ibn 'Umar.

⇨Ahmad and at-Tabarani record from Ibn 'Umar that the Messenger of Allah (peace be upon him) said, "There is no day more honorable in Allah's sight and no acts more beloved therein to Allah than those in these ten days. So say tahlil (There is no deity worthy of worship but Allah: La ilaha ill Allah), takbir (Allah is the greatest: Allahu Akbar) and tahmid (All praise is due to Allah: alhumdulillah) a lot [on those days]." [Reported by Ahmad, 7/224; Ahmad Shakir stated it is Sahih]

→The Takbir may include the words "Allahu Akbar, Allahu Akbar, la ilaha ill-Allah; wa Allahu Akbar wa Lillahil- hamd.
Translation: “Allah is the greatest, Allah is the greatest. There is no deity besides Allah and Allah is the greatest. Allah is the greatest and all praises are for Allah only.”
=======================================================

•►Fasting on the day of Arafah is a sunah an an expiration of sins.
Abu Hurairah relates that the Messenger of Allah (peace be upon him) said, "There are no days more loved to Allah for you to worship Him therein than the ten days of Dhul Hijjah. Fasting any day during it is equivalent to fasting one year and to offer salatul tahajjud (late-night prayer) during one of its nights is like performing the late night prayer on the night of power. [i.e., Lailatul Qadr]." [This is related by at-Tirmidhi, Ibn Majah, and al-Baihaqi]

⇨Regarding fasting on the day of 'Arafah; the holy Prophet (peace be upon him) also said:" 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]

→Fasting on all these days, however, is not a Wajib.
Note: The 10th of Dhul Hijjah is the day of Eid ul Adha and it is prohibited to fast on this day.

Abu Hurairah (ra) stated: "The Messenger of Allah (peace be upon him) forbade fasting on the day of 'Arafah for one who is actually at 'Arafah." [This is related by Ahmad, Abu Dawud, an-Nasa'i, and Ibn Majah]

►Allah says: “That they may witness things that are of benefit to them (reward of Hajj in the Hereafter and also some worldly gain from trade), and mention the Name of Allah on appointed days, over the beast of cattle that He has provided for them (for sacrifice).” [Surah Al-Haj:28]

O Allah enable us to make the best of these blessed days and nights and make it a means of our success in this world and in the Hereafter. Ameen.