Musnad Abu Ya'la al-Mawsili 161:20

Ishaq ibn Abi Isra'il narrated to us, he said: Musa ibn 'Abd al-'Aziz narrated to me, meaning from al-Hakam ibn Aban, he said: 'Ikrimah narrated to me, he said: Abu Hurayrah narrated to me, he said: I saw the Messenger of Allah, may Allah bless him and grant him peace, upon the pulpit while he was mentioning the hour that is in Friday. I saw him clenching his fingers and narrowing them.