Musnad Ahmad 30:3100

Waki’ narrated to us, he said: Sharik narrated to us, from ‘Abd al-Malik ibn ‘Umayr, from Abu Salamah, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The most truthful word that the Arabs have said is the word of Labid: 'Indeed, everything except Allah is false.'"