📖 Ibn 'Umar RadhiAllahu 'anhuma narrated: Allah's noble Messenger Muhammad SallAllahu 'alaihi wa sallam said, "There are no days greater and more beloved to Allah than these ten days of Dhul-Hijjah, so increase in them your declaration of the Oneness of Allah (Tahleel), your exaltation of Him (Takbeer), and your praise of Him (Tahmeed)."
Source: Musnad Ahmed 5423
Grade: Sahih (Authentic) according to Ahmed Shakir
📖 Abdullah ibn Mas’ud RadhiAllahu 'anhu narrated: Allah's noble Messenger Muhammad SallAllahu 'alaihi wa sallam said, "No good deeds can be done at a time better than these first ten days of Dhul-Hijjah." It was said, “Not even jihad (striving) in the way of Allah?” The Prophet SallAllahu 'alaihi wa sallam said, "Not even jihad in the way of Allah."
Source: Al-Mu’jam Al-Kabīr 10307
Grade: Sahih (Authentic) according to Al-Albani
📖 Ibn 'Abbas RadhiAllahu 'anhuma narrated: Allah's noble Messenger Muhammad SallAllahu 'alaihi wa sallam said, "No good deeds are better than what is done in these first ten days of Dhul-Hijjah." Some companions of the Prophet SallAllahu 'alaihi wa sallam said, “Not even jihad (striving) in the way of Allah?” The Prophet SallAllahu 'alaihi wa sallam said, "Not even jihad in the way of Allah, except for a man who goes out with his life and wealth at risk and he returns with nothing."
Source: Sahih Al-Bukhari 926
Grade: Sahih (Authentic) according to Al-Bukhari
📖 Hunaydah ibn Khalid RadhiAllahu 'anhu narrated: Some of the wives of the Prophet Muhammad SallAllahu 'alaihi wa sallam said that he would fast the first nine days of the month of Dhul-Hijjah, the day of Ashura, and three days of every month, which would be the first Monday and Thursday of the month.
Source: Sunan Abī Dāwūd 2437
Grade: Sahih (Authentic) according to Al-Albani
Al-Nawawi said, "It is part of the Sunnah to fast the first nine days of the month of Dhul-Hijjah."
Source: Al-Majmū’ Sharh Al-Muhadhab 6/386