Musnad Ahmad 30:789

Yazid narrated to us, Mas'udi informed us, from Dawud ibn Yazid, from his father, from Abu Hurayrah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, was asked about that which causes people to enter the Fire the most. He said: "The two hollows: the mouth and the private parts." And he was asked about that which causes people to enter Paradise the most. The Messenger of Allah, peace and blessings of Allah be upon him, said: "Good character."