Commentary
Note 1: The Qur’ anic expression: فَنَرُدَّهَا عَلَىٰ أَدْبَارِهَا (and turn them shaped like their backs) admits of two probabilities in this act of turning. It could either be that the features of the face are eliminated and the whole face is turned around towards the back; or, it may be that the face is flattened like the nape of the neck, devoid of all features, 'effaced.' (Mazhari, Ruh al-Ma` ani)
Note 2: When will this be is a question posed and answered by Commentators in great details. Discussing this deconfiguration (tams) and transmutation (maskh), some of them have said that this punishment will come upon the Jews before the Day of Doom, while others have said that this punishment did not come to pass because some of the Jews had entered the fold of Faith.
Maulana Ashraf Thanavi (رح) ، has said: In my opinion, that question simply does not arise because there is no single word in the Qur'an which would suggest the proposition: If you do not believe, the punishment of tams and maskh will definitely materialize. In fact, it suggests probability, that is, given their crime, they do deserve this punishment, and should He spare them from the punishment, that would be His mercy.'