“That they may witness benefits for themselves and mention the name of Allah on known days over what He has provided them of [sacrificial] animals. So eat of them and feed the miserable and poor.”

Qur’an [22:28]

The Virtues of the First Ten Days of Dhul-Hijjah

Praise be to Allaah.

Among the great seasons of worship are the first ten days of Dhul-Hijjah (the 12th month of the islamic calender), which Allaah has favoured over other days.
And the majority are of the view that the known days “appointed days” mentioned in the Qur’anic verse [22:28] are the first ten days of Dhu’l-Hijjah, because it was narrated from Ibn ‘Abbaas (may Allaah be pleased with him) that the appointed days are the first ten days of Dhu’l-Hijjah.

It was narrated from Ibn ‘Abbaas (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “There are no days on which righteous deeds are more beloved to Allaah than these ten days.” They said: “Not even jihad for the sake of Allaah?” He said: “Not even jihad for the sake of Allaah, unless a man goes out himself for jihad taking his wealth with him and does not come back with anything.” [Al-Bukhari]

These texts and others indicate that these Ten Days are better than all other days of the year, with no exception, even the last ten days of Ramadaan. But the last ten nights of Ramadaan are better than the first ten nights of Dhu’l-Hijjah, because they include Laylat al-Qadr, which is better than a thousand months. See Tafseer Ibn Katheer, 5/412.

So the Muslim should start these days with sincere repentance to Allaah, then he should do a lot of righteous deeds in general, then he should pay attention to doing the following deeds:

1. Fasting.

It is Sunnah for the Muslim to fast on the first nine days of Dhu’l-Hijjah, because the Prophet (peace and blessings of Allaah be upon him) encouraged us to do righteous deeds in the first ten days of Dhu’l-Hijjah, and fasting is one of the best of deeds, which Allaah has chosen for Himself as it says in the hadeeth qudsi: “Allaah says: ‘All the deeds of the son of Adam are for him, except fasting, which is for Me and I shall reward for it.” [Al-Bukhari]

The Prophet (peace and blessings of Allaah be upon him) used to fast on the first nine days of Dhu’l-Hijjah. It was narrated from Hunaydah ibn Khaalid from his wife, that one of the wives of the Prophet (peace and blessings of Allaah be upon him) said: “The Prophet (peace and blessings of Allaah be upon him) used to fast on the first nine days of Dhu’l-Hijjah and the day of ‘Ashoora’, and three days each month, the first Monday of the month and two Thursdays.” [Al-Albani : Sahih]

2. Reciting Tahmeed, Tahleel and Takbeer a great deal.

It is Sunnah to recite takbeer (saying Allaahu akbar (Allaah is most great)), tahmeed (saying al-hamdu Lillah (praise be to Allaah)), tahleel (saying Laa ilaaha ill-Allaah (There is no god but Allaah)) and tasbeeh (saying Subhaan-Allaah (Glory be to Allaah)), during the first ten days of Dhu’l-Hijjah, saying these words out loud in the mosques, homes, streets and every place in which it is permissible to remember Allaah, to perform this act of worship openly and proclaim the greatness of Allaah.

Men should recite out loud and women should recite quietly.

It was narrated from ‘Abd-Allaah ibn ‘Umar (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “There are no days that are greater before Allaah or in which good deeds are more beloved to Him, than these ten days, so recite a great deal of tahleel, takbeer and tahmeed during them.” [Narrated by Ahmed and classed as saheeh by Ahmad Shaakir]

The takbeer is as follows:
Allaah akbar, Allaahu akbar, laa ilaaha ill-Allaah, Allaahu akbar, wa Lillaah il-hamd (Allaah is Most Great, Allaah is Most Great, there is no god but Allaah; Allaah is Most Great and to Allaah be praise).
And there are other versions.

This takbeer has become a forsaken Sunnah nowadays, especially at the beginning of these ten days. You can hardly hear it except from a few. It should be recited out loud, so as to revive the Sunnah and remind the heedless. It was proven that Ibn ‘Umar and Abu Hurayrah (may Allaah be pleased with them both) used to go out to the marketplace during the first ten days of Dhu’l-Hijjah, reciting the takbeer out loud, and the people would recite takbeer when they heard them, i.e., the people would remember the talkbeer and each one would recite it by himself; it does not mean that they recited in unison – that is not prescribed in sharee’ah.

Reviving Sunnahs that have been forgotten brings a great deal of reward, as is indicated by the words of the Prophet (peace and blessings of Allaah be upon him): “Whoever revives one of my Sunnahs that has died out after I am gone, will have a reward like that of everyone who does it, without that detracting from their reward in the slightest.” Narrated by al-Tirmidhi, 7/443; this hadeeth is hasan because of corroborating reports.

3. Doing Hajj and ‘Umrah.

One of the greatest deeds that can be done during these ten days is Hajj to the sacred House of Allaah. Whoever Allaah helps to go on Hajj to His House and do the rituals in the required manner will – in sha Allaah – be included in the words of the Messenger of Allaah (peace and blessings of Allaah be upon him): “An accepted Hajj brings no less a reward than Paradise.”

4. Udhiyah (Sacrifice).

One of the righteous deeds that bring a person closer to Allaah in these ten days is to slaughter the sacrifice and to look for a good, fat animal and to spend money on it for the sake of Allaah.

The stipulated minimal age of the sacrificial animal is six months for sheep, one year for goats, two years for cows and five years for camels.

According to the Hadith classed as Sahih by Imam Al-Albani (may Allah have mercy on him), four (types of animals) should be avoided in sacrifice:
A One-eyed animal which has obviously lost the sight of one eye, a sick animal which is obviously sick, a lame animal which obviously limps and an animal with a broken leg with no marrow. I also detest an animal which has defective teeth.

Whoever sees the crescent of Dhul-Hijjah, and wants to slaughter a sacrifice he should not take from his hair nor from his nails.
This Ruling applies only to the one who is going to offer the sacrifice, and not to the rest of his family, and not to the one whom he appoints to slaughter the sacrifice on his behalf; it applies to both men & women

The Ruling includes the body hair and any part of the skin.

This Ruling begins from the time of Maghrib of the day before the 1st of Dhul-Hijjah and remains until the sacrifice has been offered.

And Almighty Allah chooses whatever He wills of times and places.

[ Source: https://islamqa.info/en/49042 ]

The First Ten Days of Dhul-Hijjah