In a subtle reflection on the virtues of the first ten days of Dhul-Hijjah, Hafiz Ibn Hajar says in his commentary Fath al-Bāri, “It appears that the first ten days of Dhul-Hijja are given distinction because the principle acts of worship - prayer, fasting, charity and hajj - are combined within them and this is not possible at any other time during the year.”

These days combine a range of different acts of worship which are impossible to combine during the rest of the year. Prayer, the recommendation to fast, increased charity giving including the distribution of sacrificial meat (udhiya) and hajj only take place in combination during these ten days.

—  Habib Ali al-Jifri 
It was narrated from Umm Salama that the Prophet (salla Allahu ‘alayhi wa sallam) said: “When the first ten days (of Dhu’l-Hijja) have begun, if any one of you wants to offer a sacrifice, he should not touch (i.e., remove anything from) his hair or skin.” [Muslim]