Treat the month of Zul-Hijjah, as a month of Eid.
(Saheeh Bukhari, Saheeh Muslim)

It is a sacred month.
(Saheeh Bukhari)

The first ten days (10) of Zul-Hijjah are the days of extreme virtues and sacredness. The good deeds and virtues earned during these ten days, are more virtuous and sacred as compared to noble, and good deeds and virtues of other days, save “Jehad” in which one sacrifices, both one’s life and wealth. Do good deeds and earn virtues in excess during these ten days.
(Saheeh Bukhari, Saheeh Muslim)

YOUM-E-ARAFAH: The 9th day of this month is called as Youm-e-Arafah. This is a day of great virtues and sacredness. On this day, take bath and keep fast. By keeping a fast on this day, all the sins of the preceding and the coming year, are forgiven. However, the person performing hajj, should not keep fast on the day of Arafah, during the hajj.
(Saheeh Bukhari, Saheeh Muslim)