«حَتَّى لَاحُوا كَأَسْنَانِ الْمُشْطِ فِي الِاسْتِوَاءِ»
Until they appeared as equal as the teeth of a comb.
The comb image is conspicuous, but fī al-istiwāʾ expressly names the shared property: equality or evenness. Translating as though the travelers physically acquired the shape of teeth would mistake the vehicle for the whole meaning.
The passage pictures a cohesive traveling company. Including “in equality” or “as equal as” makes the intended comparison legible. A translator should recover the specific point of resemblance, not import every property of the image.
Translation exercise
Remove “in equality” and identify the unintended comparisons that become possible.