And from among these ayat is His statement,
“O you who have believed, avoid much assumptions (for) indeed, some assumption is sin. And do not spy or backbite one another. Would one of you like to eat the flesh of his dead brother? You would detest it. And fear Allah, indeed Allah is the One Who forgives (and accepts repentance) and Merciful.” (Surah al-Hujurat:12)
And this is from among the most excellent of exemplifying analogies where in Allah has likened the shredding of the honour of a Muslim brother (through backbiting him) to the ripping of his flesh. And since the backbiter shreds his brothers’ honour in his absence, he becomes like the one who tears his brother’s flesh apart due to the absence of his soul from his body due to death – and just as the person being backbitten is unable to defend himself due to his absence, is likened to the dead person whose flesh is being ripped apart and is unable to defend it. Likewise, considering that brotherhood demands mutual mercy and relation and support whereas the backbiter attaches to it, opposite connotations such as blame and fault-finding and backstabbing, making it as if he were tearing his brother’s flesh apart.
And whereas brotherhood demands preserving, protecting and defending his brother’s honour, the backbiter takes pleasure in smirching his brother’s honour and censuring him, therefore he has been likened to devouring his brother’s flesh after tearing it up. And as the backbiter enjoys doing it and thinks good of it, he has been resembled to one who loves to eat the flesh of his brother. And his love and enjoyment in eating his brother’s flesh is a degree beyond just eating, just as eating it is a degree beyond ripping it apart.
Therefore reflect over this comparison and exemplification and its excellent arrangement and the complete correspondence between the abstract and the concrete. The description of the characterisation in the later part of the ayah preceded by the denial that anyone of them could actually love this (i.e. consuming his brother’s flesh). The case (being made) is that just as this act is reprehensible to them in their very nature, how could they love the deed of backbiting which in its nature resembles consuming one’s brother’s flesh? So Allah has established an argument against something the love to do (backbite) by employing an example of something they find reprehensible. He does this by striking a similarity between something they like to do with some which is most hateful and reprehensible to them, this reasoning compels sound mind, nature and wisdom to be strongly repelled by something which is counterpart and analagous to it. And with Allah lies success.
Paragons of the Qur’an by Ibn Qayyim al Jawziyyah Pages 69-71