As for Isḥāq ibn Banān, he has a biographical entry in Tārīkh Baghdād (6/390–391), where it is related from al-Dāraquṭnī that he considered him trustworthy. Thus, the chain of transmission is authentic, praise be to Allah.

2608 — “By Him in Whose Hand is my soul, I can indeed see the flesh of your brother between your canine teeth”—meaning, the flesh of the one whom they had backbitten.

It was recorded by al-Kharāʾiṭī in Masāwiʾ al-Akhlāq (186) and al-Ḍiyāʾ al-Maqdisī in al-Mukhtārah (2/33/2), through several routes from Abū Badr ʿAbbād ibn al-Walīd al-Ghubarī: Ḥibbān ibn Hilāl narrated to us; Ḥammād ibn Salamah narrated to us, from Thābit al-Bunānī, from Anas ibn Mālik, who said:

“The Arabs would serve one another while travelling. Abū Bakr and ʿUmar had with them a man who served them. They slept, then awoke, and he had not prepared any food for them. One of them said to the other, ‘This man’s sleeping is surely like the sleeping of your Prophet, peace and blessings be upon him’—and in another narration: ‘like the sleeping at home.’ So they woke him and said, ‘Go to the Messenger of Allah, peace and blessings be upon him, and tell him: Abū Bakr and ʿUmar convey greetings of peace to you, and they ask you for something to eat with their bread.’ He replied, ‘Return their greeting of peace, and tell them that they have already had something to eat with their bread!’ They were alarmed, so they came to the Prophet, peace and blessings be upon him, and said, ‘O Messenger of Allah, we sent to you asking for something to eat with our bread, and you said that we had already had it. What did we eat with our bread?’ He said, ‘The flesh of your brother. By Him in Whose Hand is my soul, I can see his flesh between your canine teeth.’ They said, ‘Then seek forgiveness for us.’ He replied, ‘Rather, he should seek forgiveness for you both.’”

I say: This is an authentic chain of transmission. All its narrators are trustworthy and among the narrators of Muslim, apart from Abū Badr al-Ghubarī. Abū Ḥātim—and al-Ḥāfiẓ following him—said: “Truthful.” Ibn Ḥibbān mentioned him in al-Thiqāt. A number of trustworthy hadith masters narrated from him, and he has been corroborated. Al-Ḍiyāʾ then said: “ʿAffān ibn Muslim also narrated it from Ḥammād ibn Salamah, from Thābit, from ʿAbd al-Raḥmān ibn”