Musannaf Ibn Abi Shayba 17:710

'Isa ibn Yunus narrated to us, from 'Abdullah ibn 'Abd al-Rahman ibn Ya'la, from 'Amr ibn al-Sharid, from his father, who said: I recited to the Messenger of Allah (may Allah bless him and grant him peace) one hundred rhymes of the poetry of Umayyah ibn Abi al-Salt. He would say between every rhyme, "Go on." And he said, "He was nearly a Muslim."