The same way Allah (azza wajal) created the months, he chose out of them Ramadan to give extra reward to his servants. By the same token, when he created the days, he chose the first ten days of Dhu'l Hijjah to be the best days.
This season of worship brings many benefits, such as the opportunity to correct one’s faults and make up for any shortcomings or anything that one might have missed. Some may have missed the opportunity in Ramadan or after and regret it. Now there is a chance to make up for it. Every one of these special occasions involve some kind of worship through which the slaves may draw closer to Allah (azza wajal). Likewise, every one of these special occasions have some kind of blessing though which Allah (azza wajal) grants His favor and mercy upon
whomever He wills.


The happy and successful believer is the one who makes the most of these special months, days and hours attempting to draw closer to Allah through acts of worship; he will most likely be touched by the blessing of Allah and will feel the joy of knowing that he is safe from
the flames of Hell.


? What are the ten days of Dhu'l Hijjah


The ten days of Dhu'l Hijjah are the first ten days of of the 12th Islamic calendar month called Dhu'l Hijjah. These are the days when most of the pilgrims make a journey to Makkah and perform their tasks of Hajj. Just as they have a special chance to get extra reward, the ones who were not able to go to Hajj are also given a special chance to get extra reward during these days.


? What is the significance of these 10 days


1) Allah (azza wajal) honored them by mentioning them in
the Qur’an.

Allah (azza wajal) says: "That they might witness things that are of benefit to them (i.e., reward of Hajj in the Hereafter, and also some worldly gain from trade, etc.), and mention the name of Allah on appointed days, over the beast of cattle that He has provided for them (for sacrifice)..." [al-Hajj 22:28]
The majority of scholars agree that the "appointed days" are the first ten days of Dhu'l Hijjah, because of the words of Ibn Abbas (may Allah be pleased with him and his father), "The appointed days are the first ten days (of Dhu'l Hijjah)." [This is related by al-Bukhari]
2) Allah (azza wajal) honored them when he swears an oath by them in the Qur’an as well, and swearing an oath by something is indicative of its importance and great benefit.
Allah (azza wajal) says: (interpretation of the meaning): "By the dawn; by the 10 nights" [al-Fajr 89:1-2]. Ibn Abbas, Ibn al-Zubayr, Mujahid and others of the earlier and later generations said that this refers to the first ten days of Dhu'l Hijjah. Ibn Katheer said: "This is the correct opinion."
3) They are considered the most honorable and best days ever.
Ahmad and at-Tabarani record from Ibn 'Umar that the Messenger of Allah (sallallahu alayhi wa sallam) 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 illAllah ), 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 saheeh]
Narrated Ibn 'Umar: On the Day of Nahr (10th of Dhu'l Hijjah), the Messenger (sallallahu alayhi wa sallam) stood in between the Jamrat during his Hajj which he performed (as in the previous Hadith) and said, "This is the greatest Day (i.e. 10th of Dhu'l Hijjah)." The Messenger (sallallahu alayhi wa sallam) started saying repeatedly, "O Allah! Be Witness (I have conveyed Your Message)." He then bade the people farewell. The people said, "(This is Hajjat-al-Wada)." [Bukhari 2.798]
Ibn 'Umar narrated that at Mina, the Messenger of Allah (sallallahu alayhi wa sallam) said, "Do you know what is the day today?" The people replied, "Allah and His Messenger know it better." He said, "It is the forbidden (sacred) day. And do you know what town is this?" They replied, "Allah and His Messenger know it better." He said, "This is the forbidden (sacred) town (Mecca). And do you know which month is this?" The people replied, "Allah and His Apostle know it better." He said, "This is the forbidden (sacred) month." The Messenger (sallallahu alayhi wa sallam) added, "No doubt, Allah made your blood, your properties, and your honor sacred to one another like the sanctity of this day of yours in this month of yours in this town of yours."
4) Worshipping in them is better than going to Jihad (the peak matters of worship that you can do).
There is nothing more of a collection of hadith but on jihad, but these days, worshipping is better than Jihad. The Prophet of Allah (sallallahu alayhi wa sallam) said for one to be better than one who worships in these days he must take his wealth and family and go to Jihad and does not come back and looses his wealth.