«وَالْتَفَّتِ السَّاقُ بِالسَّاقِ إِلَىٰ رَبِّكَ يَوْمَئِذٍ الْمَسَاقُ»
“Leg will be entwined with leg; on that Day the passage is to your Lord.”
Al-sāq and al-masāq echo one another, but one contains an additional letter, so the test of equal number fails.
Diagnostic point: Unequal length can yield several incomplete types depending on the number and position of added letters. This differs from merely changing syntactic case endings.