Allaah The Exalted alone is The Creator of this universe, and none but Him is entitled of choosing how this universe should be run and ruled. Allaah The Almighty Says (what means): “And your Lord Creates what He Wills and Chooses; not for them was the choice. Exalted Is Allaah and High Above what they associate with Him. “[28-68]

Allaah The Exalted rendered certain places and periods of time more honorable and superior to others because they cause rewards to be multiplied many times. This is part of the mercy towards His slaves. This is to encourage us to do more righteous deeds and to be more eager to worship Allaah, so that all Muslims would compete with each other in doing righteous deeds so as to attain such great blessings.

Among these great opportunities is the golden opportunity of the first ten days of Thul-Hijjah. Allaah The Exalted distinguished and dignified these blessed days with countless great virtues and characteristics. Allaah The Almighty Confirms the distinguished virtues of these days by swearing an oath by them, and swearing an oath by something is indicative of its significance and great benefit. Allaah, the Almighty Says (what means): “By the dawn, * And [by] ten nights, * And [by] the even [number] and the odd” [89:1-3] Many scholars suggest that the “ten nights” mentioned in this verse are the first ten days of Thul-Hijjah.

Moreover, The Prophet, sallallaahu‘alayhi wa sallam, testifies that these days are the greatest days of this life, and that doing righteous deeds during such virtuous days is better rewarded than deeds done in any other day of the year. Ibn ‘Abaas, may Allaah be pleased with him, narrated that the Prophet, sallallaahu‘alayhi wa sallam, said: "There are no days when righteous deeds are more beloved to Allaah than these ten days." The people asked, "Not even jihaad for the Sake of Allaah?" He said, "Not even jihaad for the Sake of Allaah, except the case of a man who went out giving himself and his wealth [in the Cause of Allaah] and came back with nothing." [At-Tirmithii and its original narration is mentioned in Al-Bukharii]

Furthermore, ibn ‘Umar, may Allaah be pleased with them, reported that the Prophet, sallallaahu‘alayhi wa sallam, said: " There are no days greater in the Sight of Allaah and in which righteous deeds are more beloved to Him than these ten days, so during this time utter much Tahleel ("La ilaaha ill-Allaah"), Takbeer (Allaahu Akbar) and Tahmeed (Alhamdulellaah)." [Ahmad]

Those blessed ten days include the Day of `Arafah. It was narrated on the authority of ‘Aaishah, may Allaah be pleased with her, that the Prophet, sallallaahu‘alayhi wa sallam, said:” There is no day in which Allah Frees greater number of His slaves from the Hellfire than the Day of `Arafah. Allaah Comes close [to His slaves] and boasts about them to the angels, then Asks (a rhetorical question): “What do these slaves seek?” [Muslim]

The Day of ‘Arafah is a day in which Allaah The Exalted forgives our sins; fasting on that day expiates the sins of two years.

Those blessed days include the day of An-Nahr (the day of slaughtering the sacrificial animals) ; the 10th day of Thul-Hijjah) which is the greatest day in the Sight of Allaah The Exalted; the Prophet, sallallaahu‘alayhi wa sallam, said: "The best day to Allaah The Almighty is the day of An-Nahr then the day of Al-Qarr (the 11th day of Dhul-Hijjah)" [Abu Dawood]

Such great and distinguished status of these days is due to the fact that they witness the performance of the fundamental acts of worship: prayer, fast, charity, and Hajj. These days are the only ones that witness those acts of worship together, since it is the only time of the year when Hajj is performed.

Scholars mentioned whether those 10 days are better or the last ten days of Ramadaan are. The best that has been said regarding this issue is that the ten days of Thul-Hijjah are the best days ever; whereas the last ten nights of Ramadan are the best nights ever. Since the first includes the best days ever i.e. the day of An-Nahr, the day of ‘Arafah, and the day of Tarwiyah (Thul HijjaH 8). Meanwhile the latter include the best night ever; i.e. the night of Al-Qadr.

Source: Islamweb

http://300035.dotdothktrade.tech/en/artical/1807/first-ten-days-hijjah