What is the virtue of the first ten days of Dhu al-Hijjah?

According to the preferred interpretation, the “ten nights” mentioned in verse 2 of Surah al-Fajr refer to the first ten nights of Dhu al-Hijjah, the month of Hajj. (Râzî, Mefâtîhu’l-ğayb, 31/148) Pointing to the virtue of the first ten days of Dhu al-Hijjah, the Prophet Muhammad (peace be upon him) said, “There are no deeds more beloved to Allah than those done in these ten days.” The Companions asked, “O Messenger of Allah! Not even striving in the way of Allah?” The Messenger of Allah (peace be upon him) replied, “Not even striving in the way of Allah, except for a man who goes out with his life and wealth and does not return with either.” (Abu Dawud, Sawm, 61 [2438]; see also Bukhari, ‘Eidayn, 11 [969])

The virtue of these ten days of Dhu al-Hijjah stems from the performance of the Hajj pilgrimage during this month. (Ibn Hajar, Fath, 6/110) Some of the rites of Hajj are performed during these days, while others (such as the tawaf of visitation and the stoning of the devil) are carried out in the following days of Tashreeq. It is also mentioned in narrations that fasting on the day of Arafah, the ninth day of Dhu al-Hijjah and the eve of Eid al-Adha, is highly virtuous. (Muslim, Sawm, 196-197 [1162])

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu