From Sahih Muslim (Hadith 5887):
Amr b. Sharid reported on the authority of his father that Allah's Messenger (ﷺ) asked him to recite poetry, the rest of the hadith is the same, but with this addition:"He (that is Umayya b. Abu Salt) was about to become a Muslim", and in the hadith transmitted on the authority of Ibn Mahdi (the words are) "He was almost a Muslim in his poetry
Reference: Muslim 5887