Al-Tirmidhī said:
"This is a singular ḥadīth; we know it only through this route. The transmissions of Ismāʿīl ibn ʿAyyāsh from the Syrians are sounder, whereas his narrations from the people of the Ḥijāz and Iraq contain rejected reports."

I remark: Aḥmad, Ibn Maʿīn, al-Bukhārī and others judged him trustworthy in what he transmits from the Syrians—and this report belongs to that category, for Buḥayr ibn Saʿd was a trustworthy Syrian, as were the other narrators. Thus the chain is authentic, and I do not know why al-Tirmidhī limited himself to calling it “singular” without grading it at least “good.”

Later I noticed that al-Munḏirī, in al-Targhīb (3/78), cites al-Tirmidhī as saying about it, "a good (ḥasan) ḥadīth."

I add: The same wording appears in the Būlāq edition of al-Tirmidhī (1/220), and that is the very least that can be said about it.