صِفَةٌ ... لِمَنْ قَامَتْ هِيَ بِهِ
An attribute subsisting in the knower.
The expression qāmat bihi is technical theological language. It does not picture knowledge as a physical object stored somewhere inside a person. It attributes the quality of knowing to the subject who possesses knowledge, while what is known remains the object of that awareness.
If Zayd knows that two is less than four, Zayd is the knower; knowledge is the relevant attribute; and the numerical relation is the object known. Maintaining these distinctions prevents us from identifying the external or conceptual object with the knower's quality of awareness.