لَّا يَمَسُّهُۥٓ إِلَّا ٱلْمُطَهَّرُونَ
Laa yamassuhooo illal mutahharoon
none touch it but the purified,
Muṭahharūn is the passive participle, those who have been made pure, rather than mutaṭahhirūn, those who purify themselves, and much of how this line has been read turns on that shape. The sentence is also grammatically a report of what happens rather than a command, though it has been taken as both. Commentators divide over the pronoun as well: the angels and the guarded book above, or people handling a copy.