I then found a corroborating report for the hadith on the authority of ʿUmar. Ibn Mājah (3255) and al-Bazzār, in his Musnad (1185, Kashf al-Astār), narrated it through Saʿīd ibn Zayd, from ʿAmr ibn Dīnār, from Sālim, from his father, from ʿUmar, attributed to the Prophet, peace and blessings be upon him, with the same wording, adding: “The food of four is sufficient for five and six, and blessing lies in eating together.”

Al-Bazzār said: “We know of no report from ʿUmar except through this route. ʿAmr ibn Dīnār alone narrated it, and he is somewhat weak; no one else shares him in his hadiths.”

I say: This ʿAmr ibn Dīnār is not the ʿAmr ibn Dīnār mentioned previously. That one was Meccan and trustworthy, whereas this one was Basran, known as the steward of the family of al-Zubayr, and he is weak, as stated in al-Taqrīb. This is why al-Bazzār said, “He is somewhat weak.”

I do not know, then, how al-Mundhirī could say in his al-Targhīb (2/142): “Al-Bazzār narrated it with a good chain of transmission.” Perhaps he confused the matter and thought that this ʿAmr ibn Dīnār was the trustworthy Meccan, rather than the weak Basran. He did the same elsewhere, making the error even clearer, when he said (3/306): “Al-Bazzār narrated it, and its narrators are the narrators of the Sahih.” The Basran was not among the narrators of the Sahih, so he must have meant the Meccan, for he was among the narrators used by both al-Bukhārī and Muslim.

Nevertheless, the hadith is strengthened by the totality of its chains, and is at least good. Allah knows best.