ما من أيام أعظم عند الله ولا أحب إليه العمل فيهن من هذه الأيام العشر، فأكثروا فيهن من التهليل والتكبير والتحميد
Prophet Muhammad (SAAS) taught us that there are not any days more important with Allah (SWT) nor righteous actions that are more loved to Him (SWT) than in the first ten days of Dhul-Hijjah, the month of Hajj. The Prophet (SAAS) advised us to increase in the 1st ten days saying Subhanallah, Allahu Akbar and Alhamdulillah [outloud].
Today being the 4th of Dhul-Hijjah, we have today and 6 more days to benefit from these special days as mentioned in the hadeeth above and spoken of in the first 4 ayaat of Surah Al-Fajr.
Besides increasing tahleel, takbeer, and tahmeed, it is good to perform Qiyaam Al-Layl during these nights.
Du’a should be increased on the Day of `Arafah (9th of Dhul-Hijjah, which is Thanksgiving Day this year) as well as fasting being a meritorious on this day (I know, fasting on Thanksgiving?!).
According to Imam Ash-Shafi’i (RH) in Kitab Al-Umm, one of the best nights of du’a is before `Eid, which in this case is Laylah Muzdalifah (Thanksgiving night). Proclaiming the `Eid Takbeer after the Maghrib prayer outloud in jama’ah is also meritorious.