Its chain of transmission is authentic, if Maymun lived to witness the incident, though I do not think he did.
- As for the hadith of Ibn Umar, it too has several routes.
The first is through Ata ibn Abi Rabah: “A man was praising another man in Ibn Umar’s presence, so Ibn Umar began tossing dust toward his mouth and said: ‘The Messenger of Allah, peace and blessings be upon him, said ...’” He then cited it in the wording of the heading. It was transmitted by al-Bukhari in al-Adab al-Mufrad (340) and by al-Khatib in al-Tarikh (11/107).
I say: Its chain of transmission is authentic according to the criteria of al-Bukhari in his Sahih.
The second is through Zayd ibn Aslam, who said: I heard Ibn Umar say: I heard the Messenger of Allah, peace and blessings be upon him, say—then he cited it in the wording: “Throw dust in the faces of those who lavish praise.” It was transmitted by Ibn Hibban (2008), Abu Nuaym in al-Hilyah (6/127), al-Khatib (7/338), and Ibn Asakir in his Tarikh (17/448/1), through several routes from him.
I say: This is an exceedingly authentic chain of transmission.
The third is through Abd al-Rahman ibn Jubayr ibn Nufayr, who said: “Praising your brother to his face is like drawing a sharp razor across his throat”—that is, a severe one. He said: “A man praised Ibn Umar, may Allah be pleased with him, to his face, so he said: ‘I heard the Messenger of Allah, peace and blessings be upon him, say’”—then he cited it in the aforementioned wording. Ibn Umar then took some dust and threw it in the praiser’s face, saying: ‘This is for your face,’ three times.” It was transmitted by Abu Nuaym (6/99), through the route of Baqiyyah ibn al-Walid, who said: Thawr narrated to me from Abd al-Rahman ibn Jubayr ibn Nufayr ... and he said: