فَهْمٌ يُصْلِحُ الْعَمَلَ.
Understanding that improves practice.
Understanding is presented as something with practical effects. The imperfect verb yuṣliḥ can evoke continuing or repeated improvement, though one should not infer necessary eternality from the verb form.
The correction reaches its point through the relative description: from memorisation to understanding and then to improved practice. This progression is central to the argument.