The First Ten Days

Allah(swt) swears an oath by 10 days, and swearing an oath by something is indicative of its importance and great benefit. Allah (SWT) says: “By the dawn and by the 10 nights (i.e. the first 10 days of the month of Dhul-Hijjah)…” [Qur’an 89: 1-2]
Ibn ‘Abbaas, Ibn Az-Zubayr, Mujaahid and others of the earlier and later generations, may Allah have mercy upon them, said that this refers to the first 10 days of Dhul-Hijjah. Ibn Katheer, may Allah have mercy upon him, said: “This is the correct opinion.” [Tafseer Ibn Katheer, 8/413]
The first ten days of Dhul-Hijjah have been classified as the best 10 days of the year, and the Day of ‘Arafat, on which Allah perfected His religion has been classified as the best day of the year.
Narrated by Ibn Abbas, the Prophet صلى الله عليه وسلم said, “No good deeds done on other days are superior to those done on these (first ten days of Dhul Hijja).” Then some companions of the Prophet said, “Not even Jihad?” He replied, “Not even Jihad, 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 those things.”  [Bukhaari Volume 2, Book 15, Number 86]
Imaam Ibn Taymiyyah (d. 728H) said: “The most excellent day of the week is the day of Jumuah (Friday), by the agreement of the scholars. And the most excellent day of the year is the day of an-Nahr. Some of them said that it is the day of Arafat. However, the first opinion is the correct one, since it is related in the Sunan collections that the Prophet صلى الله عليه وسلم said: “The most excellent days with Allah is the day of an-Nahr, then the day of al-Qarr (the day that the Muslims reside in Mina).” [(Saheeh) by Shaikh al-Albanee in Irwa al-Ghaleel (no: 2018). Related by Abu Dawood no: 1765].” [Majmoo al-Fatawa vol: 25, pp. 288]
The month of Dhul-Hijjah is a season of worship, and seasons of worship bring along blessings, benefits and opportunities to strengthen one’s faith and make up for shortcoming. Every one of these special opportunities involves some kind of worship, which brings the slave closer to his Lord. And Allah bestows His blessings and favours on whom He wills. The fortunate person is he who makes good use of these special months, days, and hours, while worshiping Allah. He is most likely to be touched by the blessings of Allah. Rewards of good deeds are multiplied in these days.

The Prophet صلى الله عليه وسلم said: “There are No days greater in the sight of Allaah (including Ramadhaan) & in which righteous deeds are more beloved to Him than these 10 days, so during this time recite a great deal of Tahleel (“La ilaaha ill-Allaah”), Takbeer (Allaahu Akbar) and Tahmeed (Al Hamdu Lil-laah).” [Ahmad]
According to Nasaa’i and Abu Dawood the Prophet صلى الله عليه وسلم used to fast on the first 9 days of Dhul-Hijjah and the day of ‘Ashoora’, and 3 days each month – the first Monday and 2 Thursdays of the month.
The Day of Arafaah
Regarding fasting on the Day of ‘Arafaah it was narrated from Abu Qatadah that the Messenger of Allah صلى الله عليه وسلم said: “Fasting the day of ‘Ashura’, I hope, will expiate for the sins of the previous year.” [Muslim, Vol. 1, Book 7, Hadith 1738]
Aishah (May Allah be pleased with her) reported the Messenger of Allah صلى الله عليه وسلم said, “There is no day on which Allah sets free more slaves from Hell than He does on the Day of ‘Arafah.” [Muslim, Book 11, Hadith 1277]

On the 2nd day of Hajj, the 9th Dhul Hijjah, The Day of Arafat, millions of pilgrims set out for the plains of Arafat after sunrise to attend the Khutba of Arafat and prayer their Zuhr & Asr salat combined as was the Sunnah of Rasool Allah صلى الله عليه وسلم. Thereafter they engage in supplication to Allah سبحانه وتعالى from Zuhr to Magrib, seeking forgiveness of their Lord before setting off for Muzdhalifah
Muwatta Malik: Yahya related to me from Malik from Ziyad ibn Abi Ziyad from Talha ibn Ubaydullah ibn Kariz that the Messenger of Allah, may Allah bless him and grant him peace, said, “The best dua is dua on the day of Arafa, and the best thing that I or the Prophets before me have said is ‘There is no god but Allah, alone, without any partner’ (La ilaha illa’llah, wahdahu la sharika lah.)”
It is a brief invocation, but powerful and the Sunnah of all the Prophets. It should be repeated again and again.
Fasting on Day of Arafat
This fasting is Mustahabb only for the non-pilgrims and not for the Hajis (the pilgrims) because it was not the practice of Allah’s Messenger صلى الله عليه وسلم to fast on the day of Arafat during pilgrimage and in a narration he also forbade doing so. Imaam at-Tirmidhee (ra) (d. 275H) said: “The People of Knowledge consider it recommended (Mustahabb) to fast on the day of Arafat, except for those at Arafat.” [Jaami'ut-Tirmidhee (3/377)
Perfection and completion of Islam
The day of Arafat holds great importance in Islam since this is the Day when Allah completed his revelation on His Messenger صلى الله عليه وسلم. It is reported in the Saheehayn (i.e. Saheeh al-Bukharee and Saheeh Muslim), from Umar Ibn al-Khattab (ra) that a Jewish man said to him: "O Ameer al-Mumineen (O head of the Muslims)! There is a verse in the Qur'aan, which if it was revealed on us, the Jews, we would have taken that day as an Eid (festival)." Umar asked: "Which verse?" He said: "This day I have perfected your religion for you, completed My favour upon you, and have chosen for you Islam as your religion." [al-Maidah, 5:3] Umar (ra) said: “We know on which day and in which place was this verse revealed to Allah’s Messenger صلى الله عليه وسلم. It was when he was standing in Arafat on a Friday.”
It was on this very day that the Prophet صلى الله عليه وسلم performed his pilgrimage and while he صلى الله عليه وسلم was standing on Arafat Mountain, Allah سبحانه وتعالى revealed to Him the verse:

الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الإِسْلاَمَ دِينًا

“This day I have perfected your religion for you, completed my favour upon you, and have chosen for you Islam as your religion.” (5:3)

This is the day on which Allah completed His Religion and perfected His Favour. Islam is perfect and complete. This should act as a warning to all those who call for reforming Islam or call for a British or European Islam for Muslims living in the West.
The Covenant
Arafat is the day on which Allah سبحانه وتعالى took the covenant from the progeny of Adam (as), it was reported that Ibn Abbas (ra) narrated: The Messenger of Allâh صلى الله عليه وسلم related: “When Allah سبحانه وتعالى created Adam (as) Allah سبحانه وتعالى took covenant from him in a place Naman on the day of Arafat, then He extracted from him all the descendants who would be born until the end of the world, generation after generation, and spread them out in front of Him in order to take a covenant from them also. He spoke to them face to face saying:
“Am I not your Lord?”
and they all replied: ‘Yes, we testify to it’. Allah then explained why He had all of mankind bear witness that He was their Creator and only true God worthy of worship. He said:
“That was in case you (mankind) should say on the Day of Resurrection, ‘Surely, we were unaware of this. We had no idea that You, Allah, were our Lord. No one told us that we were only supposed to worship You.”(Sahîh by Shaikh al-Albanî in Silsilah al-Ahâdîth as-Sahîhah vol: 4, no: 1623]
Indeed, the day of Arafat is a blessed day and there is no other covenant greater than this covenant!