Musnad Ahmad 30:1509

Hujayn ibn al-Muthanna Abu Umar narrated to us, Abd al-Aziz narrated to us, from Mansur ibn Adhina, from Makhul, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The servant does not attain complete faith until he abandons lying in jest, and abandons arguing, even if he is truthful."