Musnad Ahmad 25:1280

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Sulayman, from Muslim al-Batin, from Sa'id ibn Jubayr, from Ibn Abbas, from the Prophet, may Allah bless him and grant him peace, that he said: "There is no deed better than it in these days"—meaning the ten days. He said: So it was said: "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."