Sahih Muslim 5887
صحيح مسلم#5887SahihAmr 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 41:2