«حَتَّى انْثَنَى مُحْقَوْقِفًا مُصْفَرًّا»
Until he turned back bent in posture and pale in colour.
Inthanā conveys turning or returning; muḥqawqif describes a bent or hunched frame, and muṣfarr paleness or yellowing.
The paired physical descriptions serve different purposes: one shows posture, the other complexion. The traveller's suffering becomes visible, not merely stated.