Musnad Ahmad 30:1348

Fazara ibn 'Amr narrated to us, he said: Ibrahim, meaning Ibn Sa'd, narrated to us, from his father, from Abu Salamah ibn 'Abd al-Rahman, from Abu Hurayrah, who said: The Messenger of Allah (ﷺ) said: "There were among the nations before you people who were inspired (muhaddathun). And if there is anyone in this nation of mine who is one of them, it is 'Umar ibn al-Khattab."