قَوْلُ الْإِمَامِ إِمَامُ الْقَوْلِ
The imam’s saying is the leader of sayings.
In ʿaks, the order of expressions is reversed so the same elements return in opposite syntactic positions. “Qawl al-imām, imām al-qawl” exchanges the positions of qawl and imām.
Distinction: Qalb reverses the sequence of letters; ʿaks reverses the ordering of words or syntactic elements. The two operations must not be conflated.