Musnad Ahmad 25:131

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Muslim al-Batin, from Sa'id ibn Jubayr, from Ibn Abbas, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "There are no days in which righteous deeds are more beloved to Allah, the Almighty and Majestic, than these days" — meaning the ten days. They said: "O Messenger of Allah, not even Jihad in the way of Allah?" He said: "Not even Jihad in the way of Allah, except for a man who went out with his self and his wealth, then did not return with anything of that."