Musnad Ahmad 788:75

Ahmad ibn Abd al-Malik narrated to us, Musa ibn A'yan narrated to us, from Abdullah ibn Muhammad ibn Aqil, from a man, from Abu Musa al-Ash'ari, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever protects what is between his two jaws and his private parts will enter Paradise."