Al-Mundhiri recorded the following chapter in his book Al-Targhib wal-Tarhib:

الترغيب في العمل الصالح في عشر ذي الحجة وفضله

Encouragement to perform good deeds in the ten days of Dhull-Hijjah and its virtues.

Source: al-Targhīb wal-Tarhīb 2/198

Ibn Abbas reported: The Prophet, peace and blessings be upon him, said:

مَا الْعَمَلُ فِي أَيَّامٍ أَفْضَلَ مِنْهَا فِي هَذِهِ

No good deeds are better than what is done in these first ten days of Dhul-Hijjah.

Some companions of the Prophet said, “Not even jihad in the way of Allah?” The Prophet said:

وَلَا الْجِهَادُ إِلَّا رَجُلٌ خَرَجَ يُخَاطِرُ بِنَفْسِهِ وَمَالِهِ فَلَمْ يَرْجِعْ بِشَيْءٍ

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: Ṣaḥīḥ al-Bukhārī 926, Grade: Sahih

In another narration, the Prophet said:

مَا مِنْ عَمَلٍ أَزْكَى عِنْدَ اللَّهِ عَزَّ وَجَلَّ وَلَا أَعْظَمَ أَجْرًا مِنْ خَيْرٍ يَعْمَلُهُ فِي عَشْرِ الْأَضْحَى

No deeds are more pure to Allah, nor greater in reward, than good deeds performed in the ten days of the month of sacrificing.

Source: Sunan al-Dārimī 1727, Grade: Hasan

Al-Qasim ibn Abi Ayyub reported:

وَكَانَ سَعِيدُ بْنُ جُبَيْرٍ رضي الله عنه إِذَا دَخَلَ أَيَّامُ الْعَشْرِ اجْتَهَدَ اجْتِهَادًا شَدِيدًا حَتَّى مَا يَكَادُ يَقْدِرُ عَلَيْهِ

When Sa’id ibn Jubayr, may Allah be pleased with him, reached the first ten days of Dhul-Hijjah, he would exert himself in worship so greatly that he would nearly overwhelm himself.

Source: Sunan al-Dārimī 1774

Abdullah ibn Mas’ud reported: The Messenger of Allah, peace and blessings be upon him, said:

مَا مِنْ أَيَّامٍ الْعَمَلُ فِيهِنَّ أَفْضَلُ مِنْ أَيَّامِ الْعَشْرِ

No good deeds can be done at a time better than these first ten days of Dhul-Hijjah.

It was said, “Not even jihad in the way of Allah?” The Prophet said:

وَلا الْجِهَادُ فِي سَبِيلِ اللَّهِ

Not even jihad in the way of Allah.

Source: al-Mu’jam al-Kabīr, Grade: Sahih

Jabir reported: The Messenger of Allah, peace and blessings be upon him, said:

مَا مِنْ أَيَّامٍ أَفْضَلُ عِنْدَ اللَّهِ مِنْ أَيَّامِ عَشْرِ ذِي الْحِجَّةِ

No days are better to Allah than the first ten days of Dhul-Hijjah.

A man said, “O Messenger of Allah, are they better or time spent waging jihad in the way of Allah?” The Prophet said:

هُنَّ أَفْضَلُ مِنْ عِدَّتِهِنَّ جِهَادًا فِي سَبِيلِ اللَّهِ وَمَا مِنْ يَوْمٍ أَفْضَلُ عِنْدَ اللَّهِ مِنْ يَوْمِ عَرَفَةَ يَنْزِلُ اللَّهُ إِلَى السَّمَاءِ الدُّنْيَا فَيُبَاهِي بِأَهْلِ الْأَرْضِ أَهْلَ السَّمَاءِ فَيَقُولُ انْظُرُوا إِلَى عِبَادِي شُعْثًا غُبْرًا ضَاحِينَ جَاءُوا مِنْ كُلِّ فَجٍّ عَمِيقٍ يَرْجُونَ رَحْمَتِي وَلَمْ يَرَوْا عَذَابِي فَلَمْ يُرَ يَوْمٌ أَكْثَرُ عِتْقًا مِنَ النَّارِ مِنْ يَوْمِ عَرَفَةَ

They are better than time spent waging jihad in the way of Allah. No day is better to Allah than the day of Arafat. Allah descends to the lowest heaven and he boasts to the inhabitants of the heavens about the inhabitants of the earth, saying: Look at my servants, appearing disheveled and dusty. They came from every mountain pass hoping for my mercy. They do not see my punishment, yet they do not see that on no day are more saved from Hellfire than the day of Arafat.

Source: Ṣaḥīḥ Ibn Ḥibbān 3853, Grade: Sahih

n another narration, the Prophet said:

أَفْضَلُ أَيَّامِ الدُّنْيَا أَيَّامُ الْعَشْرِ عَشْرِ ذِي الْحِجَّةِ

The best days in this world are the first ten days of Dhul-Hijjah.

Source: al-Amālī al-Khamīsīyah 1223, Grade: Sahih li ghayrihi