«والشمس كالمرآة في كف الأشَلّ»
The sun is like a mirror in the hand of someone whose hand trembles.
The image suggests the shimmering appearance of a bright round object, with movement causing changing reflections. The swaying mirror, light and shifting visual impression form one composite perceptual scene.
It is insufficient to say merely that both the sun and a mirror shine. The expressive point lies in their appearance when light and motion are considered together. Individual features may be mediated by poetic imagination rather than identical literal movements in the physical objects.