It is narrated from Ibn Abbas that the Prophet (peace be upon him) of said: "There are no days in which righteous deeds done in them...
It is narrated from Ibn Abbas that the Prophet (peace be upon him) of said: "There are no days in which righteous deeds done in them are more beloved to Allah than these days, i.e. the ten days (of Dhul-Hijjah). They said: O Messenger of Allah, not even Jihad in the path of Allah? He said: Not even Jihad in the Path of Allah, the Most High, except if a man goes out (for Jihad) with his self and his wealth, then he doesn't return with anything from that." (Al-Bukhari, Abu Dawud and others. The exact wording is that of Abu Dawud)