First ten days of Dhul Hijjah
K’ab Ibn Malik Radiallahu anhu says:
The period most beloved to Allah is the four sacred months, (i.e. Dhul Qa’dah, Dhul Hijjah, Muharram and Rajab). And from these four sacred months Allah admires the month of Dhul Hijjah. And (although the entire month of Dhil Hijjah is blessed and sanctified), Allah has additionally favoured the first ten days of this month.