Ezekiel 42:5
Now the upper chambers were shorter: for the galleries were higher than these, than the lower, and than the middlemost of the building.
Cross-reference
Ezekiel 42:6
Parallel
Ezekiel 42:6 continues the structure — three stories without pillars — explaining why the upper chambers are set back as mentioned here.
Ezekiel 41:7
Contrast
Ezekiel 41:7 shows the temple's side chambers widening as they rise — opposite to the shrinking upper chambers here, highlighting different design purposes.