Ibn Abī Shaybah and Aṭ-Ṭabarānī narrated (and this is the latter's wording) on the authority of 'Abdullāh ibn Mas'ūd raḍhiyallāhu 'anhu, that he said:

“We were with the Prophet ﷺ and a man got up (and left), afterwards another man spoke ill of him. So the Prophet ﷺ said to him: “Takhallal(1).” He replied: “What do I need to do Takhallul from? I didn't eat meat.” The Prophet ﷺ said: “You ate your brother’s flesh.” [Authenticated by Sheikh Albāni in his checking of 'Ghāyatul Marām Fī Takhrīji Aḥādīthil Ḥalāli wal Ḥarām'] ____________________ (1) to remove pieces of food from between the teeth