لَيْسَ كَمِثْلِهِ شَيْءٌ
There is nothing comparable to anything like Him.
The contrast between “laysa ka-llāhi shayʾ” and “laysa ka-mithlihi shayʾ” helps explain the rhetorical force. Both deny likeness, while the latter can make the denial more emphatic by employing a further level of expression through “like.”
This is more subtle than a simple transfer between descriptive words. The denial of similarity is conveyed through the implication of the formulation. The analytical focus here is the rhetoric of negation, not introducing unsupported theological assumptions.