It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "There are no days in which good deeds are more excellent than these ten days (the first ten days of Dhu al-Hijjah)." It was said: Not even jihad in the path of Allah? He (peace and blessings be upon him) said: "Not even jihad in the path of Allah."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10417