Musnad Ahmad 31:451

Waki’ narrated to us, Isma’il ibn Muslim narrated to me, Abu al-Mutawakkil narrated to us, from Abu Sa’id, from the Prophet, peace and blessings of Allah be upon him, who said: "People will emerge from the Fire after they have been burned and become charcoal, then they will enter Paradise. They will grow therein just as the vegetation grows in the silt of a flood."