First 10 days of
dhul hijjah

وَالْفَجْرِ وَلَيَالٍ عَشْرٍ

Ibn Abbas tells us that The Prophet (as), said, “No good deeds are better than what is done in these first ten days of Dhul Hijjah.” Some companions asked, “Not even jihad in the way of Allah?” And The Prophet(as) replied “Not even jihad in the way of Allah, except for a man who goes out with his life and wealth at risk and he returns with nothing.” (Sahih Bukhari 926)